Car Was Hot And Shut Off - Wouldn't Start...

[kings1527]

....until it cooled off for a bit and then everything was fine.

So I'm driving in SoCal yesterday on a pretty hot day (around 90 degrees) but in a lot of traffic on surface streets

-Full AC going and my engine temp was constantly about 200-210 degrees for about an hour, 1.5 hours max
-As I would drive, sometimes I'd press the clutch in and with the AC on, my volts dropped off (DMCH 120V alternator) and a couple times the car died. It restarted just fine.
-I now get on the freeway and driving at around 70MPH and suddenly the car dies. No warning or anything. I coast off to the shoulder and get towed home.
-I get home about an hour later and the car starts up fine. Once things cooled off, everything seemed to operate as normal.

From threads I'm seeing, it seems like my ignition coil or distributor coil (pickup coil located inside the distributor) could be going bad. Any other ideas? What's the best way to test those two items? I'd much rather swap out an ignition coil than the pickup coil.

Thanks in advance.

[Bitsyncmaster]

So it only has a problem when it's very hot. Those are tough problems to fix since it could be a failure of one or more of many things.

Only clue we have is you noticed a voltage drop. How low did it go and was it only because your engine RPM was low?

[kings1527]

So it only has a problem when it's very hot. Those are tough problems to fix since it could be a failure of one or more of many things.

Only clue we have is you noticed a voltage drop. How low did it go and was it only because your engine RPM was low?

It would drop off to around 12.5V or so and that was directly tied into my RPMs. When Id press the clutch while coming to a stop with the AC on, my volts dropped off a couple times and the car died. But yes, the volts dropping off was from the RPMs.

[Farrar]

Is your alternator fairly new? Sometimes hot conditions can take their toll on an older alternator.

[kings1527]

Is your alternator fairly new? Sometimes hot conditions can take their toll on an older alternator.

Yes, it's about 2.5 years and 12k miles old.

[Bitsyncmaster]

Now we don't know if the engine RPM was dropping (below 775 RPM idle speed) because of low voltage or if your constant idle system is just not responding fast enough. You may also have another problem because of the no hot restart.

Does your RPM "undershoot" (go below 775 RPM) when the engine is not hot?

Below 775 RPM I would expect the voltage and oil pressure to dip....that would be normal.

[kings1527]

Now we don't know if the engine RPM was dropping (below 775 RPM idle speed) because of low voltage or if your constant idle system is just not responding fast enough. You may also have another problem because of the no hot restart.

Does your RPM "undershoot" (go below 775 RPM) when the engine is not hot?

Below 775 RPM I would expect the voltage and oil pressure to dip....that would be normal.

My system is tight regarding hot starts. New accumulator, PPR o-ring, etc. All's working well with that.

My system is only undershooting when the engine is hot. And the voltage only drops off when I push in the clutch and drop the RPMs by doing that. It's like the sudden drop in RPMs from the 1500 range down to sudden idle rpm with the electrical system being taxed by the AC causes a stall very occasionally. But then this whole hing was a bit different. No clutch, no rpm drop off. Just completely cut out.

[DMCMW Dave]

Check the connections on the ballast resistor and coil. They get very hot and "let go" and can self-heal when they cool off. Same thing with the internals of the RPM relay. Check your fuses for corrosion/melting.

[PJ Grady Inc.]

Yes these connections are highly suspect and cause lots of intermittent problems. I always replace these if there's any sign of corrosion with OEM connectors.

I suspect the pickup coil as another even more likely cause but the only way to positively diagnoss it is to drive around with a multimeter until it fails again and check for continuity at the LT pickup lead from the distributor to the ignition ECU.

Rob


Check the connections on the ballast resistor and coil. They get very hot and "let go" and can self-heal when they cool off. Same thing with the internals of the RPM relay. Check your fuses for corrosion/melting.

[kings1527]

Thanks everybody.

I checked the ballast resistor connections and they're very tight but show a little bit of corrosion. I'll go ahead and replace the connectors since that's easy to do but I'll most likely look to replace the pickup coil since I was going to do a major service on it sometime this year. I'll just end up doing it sooner. I was going to replace the heater valve anyways once I get the manifold off.

So I read in a different thread where Dave MW mentioned that it's much easier to replace the pickup coil with the distributor out of the car since it's easy to drop and lose things in the process. Once I take the distributor out, my only concern is refitting the distributor without messing up the timing.

M:01:02 in the manual gives a walkthrough on how to do it but they also mention to make marks on everything while you first take it out. So, theoretically, if I make a few marks with a Sharpie between the distributor and cylinder head, remove the distributor, replace the pickup coil, and then re-install the distributor EXACTLY the way it was by following my Sharpie marks...everything would work and I wouldn't have to do anything else, correct?

And Rob, can you give me a better location of the location of those wires so I can test continuity? I'm not familiar with the location you gave. I'll definitely drive around with my multimeter now just in case it happens again. And from what I've read, it should be about 550 ohms cold and about 700 ohms when hot? Does that sound about right?

Thanks again!

[Bitsyncmaster]

I'm thinking it's your idle system undershoots to far when hot. But that does not explain the no start problem.

I'm thinking of some simple things to do. First would be to bump up your curb idle screw. That is the lower screw on the throttle arm. You want that curb idle to be set as high as you can but your limited by the idle not holding 775 with a hot engine (no loads). Also check your idle switch screw to make sure it "clicks" the switch at idle and does not bottom out the switch completely.

[David T]

I'm thinking it's your idle system undershoots to far when hot. But that does not explain the no start problem.

I'm thinking of some simple things to do. First would be to bump up your curb idle screw. That is the lower screw on the throttle arm. You want that curb idle to be set as high as you can but your limited by the idle not holding 775 with a hot engine (no loads). Also check your idle switch screw to make sure it "clicks" the switch at idle and does not bottom out the switch completely.

We had a poster a while back who would drive his car and after about 20 minutes, (always 20 minutes!) always at the same block, his car would die. It turned out to be his impulse coil. Sounds like you have a similar problem. The other possibility is if your voltage gets too low the ignition ECU will stop working. If so the car should start right up if you can get the voltage back either with a battery pack or a jump. Neither would help if it is the impulse coil. At least not till the car has a chance to cool off. If you do replace the impulse coil you must mark everything, remove the distributor, take it all apart, replace the coil, check the gaps on the coil, put it back together and check the timing with a timing light. Just because you put everything back exactly as it was does not mean it was right BEFORE you took it apart. You should also confirm operation of the vacuum and mechanical advance. Doubtful it is a bad connection on the ballast resistor, that usually won't kill a running motor, it usually prevents a cold one from starting.

[kings1527]

An update on my situation. I decided to drive around with my multimeter in case it happened again (actually, I got a bit lazy and put off replacing the pickup coil) but was able to re-create the problem with good news/bad news.

The good: the coil was reading 0.75 ohms when it cut out. I think that's a pretty good indicator where the problem lies.

The bad: I'm stranded as we speak. Luckily in a parking lot so that's the best case scenario.

Unless I have two problems going on, it seems an early failure warning of a doomed pickup coil is the low RPM and subsequent engine cut out I was talking about earlier. It became more and more frequent as time went on. Until it failed again. And definitely heat related.

So now all I have to do is get home and get to work on it. Problem solved. Almost.

[Bitsyncmaster]

I don't like autoranging meters. Are you sure your meter was reading 0.75 ohms and not 0.75 Kohms?

[kings1527]

I don't like autoranging meters. Are you sure your meter was reading 0.75 ohms and not 0.75 Kohms?

Mine isn't auto ranging. I have the action cp7677 and had it set to 20k ohms on the dial. I'm not a multimeter wizard but I believe I had that setting correct. Please let me know if not!

[kings1527]

Now I'm thinking I might've had the wrong setting. I might've been looking at a perfectly normal ohm reading when hot.

Now I'm really puzzled. I looked at my connections and they all look ok and tight, but I might as well replace them all and clean the connections.

Where can I get those connectors? Are they common at Pep Boys or the like?

And what else could I be looking at with this? Some mentioned the ignition ecu. What about the ignition coil?

Today, as soon as I let it cool off about an hit and a half or two, it fired right back up again and all was fine.

Thanks.

[Bitsyncmaster]

The 20 K setting would read in Kohms. So you were reading 750 ohms with a reading of 0.75

I just removed the connector on the wire from the pickup coil and soldered the wires without connectors. It still could be a lot of things that fail with heat but that connector was real badly corroded on my car.

[kings1527]

I'm focused now on the ignition coil since those seem to show similar symptoms and mine might very well be original. I measured resistance between the posts (all wires disconnected) and it was about 0.62 ohms. Then I measured between the center terminal and one of the side terminals and that was about 9220 ohms.

Are these good numbers? I've read the posts should be 0.75-0.81 and the center should be 10000-11000. Seems like I might be a bit low and I wish I measured when the car was symptomatic.

[Chris 16409]

No one has mentioned an overheated fuel pump. That is something to check too. I think it is more likely for the fuel pump to overheat in the LA heat rather than some quirky ignition gremlins. When was the last time you replaced your fuel pump and pickup hose? Also, since you had your AC on and the fans were blowing a bunch of hot air on to the fuel tank, further leads to me think your pump might be dying.

[kings1527]

No one has mentioned an overheated fuel pump. That is something to check too. I think it is more likely for the fuel pump to overheat in the LA heat rather than some quirky ignition gremlins. When was the last time you replaced your fuel pump and pickup hose? Also, since you had your AC on and the fans were blowing a bunch of hot air on to the fuel tank, further leads to me think your pump might be dying.

Thanks Chris. But I did replace my OEM fuel pump system with the DMCH combo unit. I've gone through the overheated fuel pump problem before and this is totally different. No sound from the pump and obviously no pickup tube to contend with. For my car to get crazy in the "old days" with the OEM fuel pump, that took about three hours of driving non-stop in temperatures easily above 100. It happened once I got off the freeway offramp. It only happened to me once and then I said goodbye to the old setup.

[David T]

No one has mentioned an overheated fuel pump. That is something to check too. I think it is more likely for the fuel pump to overheat in the LA heat rather than some quirky ignition gremlins. When was the last time you replaced your fuel pump and pickup hose? Also, since you had your AC on and the fans were blowing a bunch of hot air on to the fuel tank, further leads to me think your pump might be dying.

The next time it dies either check for spark or shoot a little Ether into it to confirm lack of spark or lack of fuel. Your symptom sounds like a bad impulse coil. The ignition coils either work or don't, they don't fix themselves by cooling. The ignition ECU also works or doesn't and they don't generally fail. Changing the impulse coil is a pain because you have to take the distributor out and take it all apart.

[kings1527]

The next time it dies either check for spark or shoot a little Ether into it to confirm lack of spark or lack of fuel. Your symptom sounds like a bad impulse coil. The ignition coils either work or don't, they don't fix themselves by cooling. The ignition ECU also works or doesn't and they don't generally fail. Changing the impulse coil is a pain because you have to take the distributor out and take it all apart.

Thanks David, but with the readings I was getting on the impulse coil when I got the car to act up again, wouldn't that confirm that the impulse coil was ok? When it was hot and symptomatic, the impulse coil was reading over 700 ohms.

[kings1527]

And I seem to remember today that the tachometer was fluttering as I was trying to start it. From what I've read, that would rule out the RPM relay, impulse coil, and ignition ECU. Even more likely this could be a ignition coil problem?

[Bitsyncmaster]

I agree we need to narrow down the cause to be fuel or ignition. Also agree you should carry a can of starting fluid to help you find the cause. So when the problem happens again, quickly remove the air cleaner, give it a shot of starting fluid and see if it makes the engine "spudder". You may have to do the test a few times depending on how fast the problem cures itself. The gas in the tank will get very hot with less than an hour of driving on a 100 deg summer day.

[kings1527]

I agree we need to narrow down the cause to be fuel or ignition. Also agree you should carry a can of starting fluid to help you find the cause. So when the problem happens again, quickly remove the air cleaner, give it a shot of starting fluid and see if it makes the engine "spudder". You may have to do the test a few times depending on how fast the problem cures itself. The gas in the tank will get very hot with less than an hour of driving on a 100 deg summer day.

Sounds good. I'll try to get it to do it again.

I had someone mention to me about the yellow wire (capacitor?) coming off the terminal of the ignition coil. They referred to it as a "condenser" Dave (or anyone): any knowledge on this or the possibility that this is factoring into my problem? Over on Today, I saw a post that mentioned this wire is only related to reducing radio interference but this other guy that I talked to said the condenser was the cause of his problem.

[Kherns]

I'd rather say, this could be the problem.
Happenned to several owners here in France, and recommended by our Guru !:thumbup:
This saved a friend o'mine whose DeLorean was blacking out every hours or so, and
he had to let it cool down....once he unplugged this yellow litle bugger, problem disappeared.
Alex's case looks really similar to that.

[David T]

I'd rather say, this could be the problem.
Happenned to several owners here in France, and recommended by our Guru !:thumbup:
This saved a friend o'mine whose DeLorean was blacking out every hours or so, and
he had to let it cool down....once he unplugged this yellow litle bugger, problem disappeared.
Alex's case looks really similar to that.

If you think it is the condenser just remove it and see what happens. Doubtful it it the cause but possible. It is there to reduce interference on the radio. Taking measurements is not a good way to confirm since you have to disturb it just to check it. The Ether is a better and faster way to check. If you get no response you KNOW you have no spark.

[kings1527]

Bad ignition coil.

I replaced it the other day and all seems to be well. Before swapping in the new coil, I drove to work and it stalled out on me once but that was it. Later in the day, I installed the new coil and I couldn't get it to stall once even while under heavy load with the AC and headlights on. Stalling was becoming a common occurrence. I haven't had the chance to drive it on a real hot day and test it that way but there's already been a noticeable improvement.

So to recap:
-car would occasionally stall out while driving. Car would start right up again.
-after driving for a long time and pre-heating the engine compartment, the car would suddenly die and wouldn't start for at least an hour. Afterwards, it'd fire up and everything was fine again.
-after the car dies from the heat and I'd try to start it, the tachometer would flutter during cranking. Apparently that test rules out the impulse coil and ignition ECU.

Thanks again for the help!

[DMCMW Dave]

What kind was the one that failed?

[kings1527]

What kind was the one that failed?

It was what I presume to be original to my car Bosch OEM coil. I don't have any record of a previous owner changing it out and it definitely looked like it has been in the car for a long time.

[DMCMW Dave]

Thanks. Just a data point. I've probably seen two failures of original coils, a few more of aftermarket coils in a much smaller population. In either case a low failure-rate part.

[David T]

Thanks. Just a data point. I've probably seen two failures of original coils, a few more of aftermarket coils in a much smaller population. In either case a low failure-rate part.

As Dave S says, the failure rate of the OE ignition coils is very low. It is just as likely you had a bad connection to the coil and your act of replacing it cleaned the connections. Or you have a bad connection on the ballast resistor and the original coil was sensitive to it. In any case I would watch and see if the problem reoccurs. It is always hard to really KNOW you fixed an intermittent problem.

[kings1527]

So it looks like I was fighting two battles. The first was the idle problem that would die. I'd be driving then come to a stop and press in the clutch. In doing so, sometimes my RPMs would drop to around 500 and then the idle system would kick in and idle well. But sometimes the RPMs would drop down all the way and the engine would die. But then it'd start right back, particularly if I just popped the clutch if I was still moving.

Solution: dirty idle speed motor. I cleaned it and then lubed it and it's never done it again over about the past 500 miles.

My original problem remains. I'm driving and keeping things preheated in the engine compartment on a hot day with the AC on. And then the car cuts out and won't start for about an hour. Once it cools off, all set to go. Here's what I know:

-replaced the ignition coil. Apparently that wasn't it.
-getting 750 ohms when I test the pickup coil.
-checked fuse 8. It's good and I get good power at the fuse.
-ballast resistor seems ok.
-my tach flutters when I try to start it. Apparently that rules out the pickup coil again but also the ignition module.

So being without any ether, I decided to do a plug swap with the WUR and it fired right up and ran. I go back to the standard connections and no go. So obviously I'm looking at a fuel problem.

I have a spare rpm relay that I'll have to try out. But what else? Fuel pump? I have the updated integrated pump/sender unit. Anyone know of problems with them when overheated?

Thanks!

[David T]

If the plug swap gets you going that is a sure sign that you aren't holding rest pressure. Usually the fuel accumulator but can also be a bad check valve or a leaky PPR. As for the dying, I would still guess the impulse coil. By the time you check it with an ohmmeter it cools off and looks good again.

[kings1527]

If the plug swap gets you going that is a sure sign that you aren't holding rest pressure. Usually the fuel accumulator but can also be a bad check valve or a leaky PPR. As for the dying, I would still guess the impulse coil. By the time you check it with an ohmmeter it cools off and looks good again.

Thanks David. I measured the impulse coil with my multimeter about 1 minute after this all happened. I've been driving around with it in the trunk just in case and I'm glad I did. I'm sure the impulse coil takes longer to cool off.

I don't believe this to be a rest pressure issue. This situation is very similar to a fuel pump pickup hose problem: once it happens, I have to wait for things to cool down and then it runs fine again. Unlike a rest pressure problem, the more I crank the engine, it doesn't do anything. It has to rest and cool off before it starts again.

Will a plug swap still work if the fuel pump is not working? In other words, if a plug swap works does that mean everything is fine with the pump?

[Bitsyncmaster]

-my tach flutters when I try to start it. Apparently that rules out the pickup coil again but also the ignition module.

I guess you mean the tach jumps up and down rather than show a constant cranking RPM.

I will check what mine does later today. I will pull the high voltage coil lead to rather than a resistor wire to keep the engine from starting.

[David T]

Thanks David. I measured the impulse coil with my multimeter about 1 minute after this all happened. I've been driving around with it in the trunk just in case and I'm glad I did. I'm sure the impulse coil takes longer to cool off.

I don't believe this to be a rest pressure issue. This situation is very similar to a fuel pump pickup hose problem: once it happens, I have to wait for things to cool down and then it runs fine again. Unlike a rest pressure problem, the more I crank the engine, it doesn't do anything. It has to rest and cool off before it starts again.

Will a plug swap still work if the fuel pump is not working? In other words, if a plug swap works does that mean everything is fine with the pump?

The plug swap won't work if the fuel pump isn't working. This also means the pick-up hose, baffle and filter are OK. It can't hurt to peek inside the tank and clean it out anyway. One way to help diagnose this is to put a fuel pressure gauge on the system.

[Bitsyncmaster]

I just pulled my high volt coil wire and tried to start the engine. The Tach bounced between 250 to 500 RPM with a pretty consistent bounce.

The cold start valve pumps very little gas and does not need much fuel pressure to work. So doing the plug swap is not really proving your pump and pickup are good.

[David T]

I just pulled my high volt coil wire and tried to start the engine. The Tach bounced between 250 to 500 RPM with a pretty consistent bounce.

The cold start valve pumps very little gas and does not need much fuel pressure to work. So doing the plug swap is not really proving your pump and pickup are good.

It proves the pump is running. That proves out the RPM relay, all the wiring, the inertia switch, and the ignition switch. It helps to narrow things down a lot. You are right it is possible the pick-up hose is collapsing or kinking and/or the inlet filter may be dirty.

[kings1527]

I just pulled my high volt coil wire and tried to start the engine. The Tach bounced between 250 to 500 RPM with a pretty consistent bounce.

The cold start valve pumps very little gas and does not need much fuel pressure to work. So doing the plug swap is not really proving your pump and pickup are good.

Thanks guys. I feel like I'm making headway.

And just to clarify, I don't have the OEM fuel pump anymore. I have the updated combo unit so obviously no pickup line to contend with. But with the old system, I experienced a collapsing pickup line and this is very similar stuff.

I'm with you, Dave M. I opened up the fuel pump panel and disconnected the the fuel pump to guarantee no power to only the fuel pump. Then I did a plug swap to see if a plug swap will work without the fuel pump and it did. It fired up but with a high RPM for a few seconds but it ran, just like when I did it yesterday. It recreated everything perfectly. Like you said DM, the CSV needs very little pressure to open and during a plug swap I think it was just taking fuel from my rest pressure which I know is good.

I tried disconnecting the RPM relay and see what that did while doing a plug swap but while I was cranking the engine, it was a totally different sound and it never started. Very different from yesterday so I'd have to rule out (in a very caveman way) an intermittent RPM relay problem. I also learned that a bad RPM relay not only cuts out the fuel pump but the electrical system as well.

My inertia switch is grounded directly to the frame, so I've effectively bypassed it for fuel purposes. I'd have to say it's good.

All things are pointing to a fuel pump problem in my mind. Would you agree?

One important thing to note is that the times this was happening to me, I was at either a half tank of fuel or less. Hot fuel coming back to the tank on the return line and causing a problem with the pump? Once it cools off, it starts again and everything is fine. I drove it in to work today, no problem. A friend of mine with a boat said he had the exact same thing happening with his boat.

[Bitsyncmaster]

So far I have not heard of any problems with the new pump/sender combo with hot fuel. No reports of the buzzing that the OEM pump would do. I've measured that fuel in the tank gets over 130 degrees F after a drive.

[kings1527]

My engine shutdown problem has been traced to a bad fuel pump. And the pump I had in there was the new pump/sender combo. However, here's where I think I went wrong and what I'd recommend for people living in hot(ter) climates:

1) It's been well documented that the hot fuel situation in our cars can reach 120+ degrees, thanks to testing by Dave M. The very likely culprit is fuel returning back to the tank via the return line and the original fuel pump setup would become symptomatic (loud fuel pump buzz, collapsing hose, stalling) when fuel capacity would be under 1/2 tank.

2) The new combo setup takes the hose out of the equation, but be careful. The fuel temp doesn't change.

3) Electric fuel pumps rely on fuel to keep it on the cooler side and for lubrication. If you keep sending hot fuel back to it, it will cause premature wear. Not only in our cars but in other cars, too. This is the most common cause of fuel pump failure, from what I've read.

4) I've had a habit over the past two years of only filling my car up when the low fuel light comes on or when it gets close to it. By this time in Southern Calif, the fuel pump has been taking a beating with hot fuel.

5) As electronics heat up and become worn out, they draw more amperage. Once the pump had been damaged to a certain point, as it would heat up the electrical demands of the pump would exceed the car's ability and the result would be the pump shutting down. It would start back up after the pump had time to cool off. (I'm about 75% certain with this point)

6) As time went on, the car would become symptomatic faster and with less heat.

So, the solution? I'd recommend making it a habit to fill up at a half tank particularly if you live in a hot area. I think that'll preserve the pump a lot better by keeping the fuel on the cooler side. After installing a new unit, I drove it around with the AC on the entire time and an engine temp of about 200 degrees for an hour and there wasn't even the slightest bit of a problem.

[Bitsyncmaster]

All else being equal, the copper wire in the fuel pump resistance would increase (a little) as it heats. That would result in less current driven with a constant voltage. But if the load on the pump increases due to bearings, less lubrication (the hot fuel) the current will go up.

[David T]

My engine shutdown problem has been traced to a bad fuel pump. And the pump I had in there was the new pump/sender combo. However, here's where I think I went wrong and what I'd recommend for people living in hot(ter) climates:

1) It's been well documented that the hot fuel situation in our cars can reach 120+ degrees, thanks to testing by Dave M. The very likely culprit is fuel returning back to the tank via the return line and the original fuel pump setup would become symptomatic (loud fuel pump buzz, collapsing hose, stalling) when fuel capacity would be under 1/2 tank.

2) The new combo setup takes the hose out of the equation, but be careful. The fuel temp doesn't change.

3) Electric fuel pumps rely on fuel to keep it on the cooler side and for lubrication. If you keep sending hot fuel back to it, it will cause premature wear. Not only in our cars but in other cars, too. This is the most common cause of fuel pump failure, from what I've read.

4) I've had a habit over the past two years of only filling my car up when the low fuel light comes on or when it gets close to it. By this time in Southern Calif, the fuel pump has been taking a beating with hot fuel.

5) As electronics heat up and become worn out, they draw more amperage. Once the pump had been damaged to a certain point, as it would heat up the electrical demands of the pump would exceed the car's ability and the result would be the pump shutting down. It would start back up after the pump had time to cool off. (I'm about 75% certain with this point)

6) As time went on, the car would become symptomatic faster and with less heat.

So, the solution? I'd recommend making it a habit to fill up at a half tank particularly if you live in a hot area. I think that'll preserve the pump a lot better by keeping the fuel on the cooler side. After installing a new unit, I drove it around with the AC on the entire time and an engine temp of about 200 degrees for an hour and there wasn't even the slightest bit of a problem.

There is no circuit breaker (or equivalent) that would shut off the pump and after cooling restart the pump so I disagree with #5. The main source of heat is the 2 cooling system pipes going to and from the radiator so I disagree with #1. One thing you could do (other's have done this) is to create a small heat exchanger by wrapping a coil of copper tubing around the A/C accumulator and passing fuel through it. Another thing is to add an air dam behind the radiator so the air from the cooling fans is deflected downwards and away from the fuel tank. The OEM set-up can work well but I would add a spring inside the pick-up hose so it can't soften up and collapse or kink. A collapsed hose is the worst of all cases since now the pump is getting NO lubrication and of course the motor can't run. I can't comment on the new pump set-up from DMCH since I don't have much experience with it. Yes, the problem tends to be worse the lower the fuel level and less mass of fuel that can absorb heat. More fuel also provides a head so the pump doesn't work as hard. It also gives you more range so all around it is the easiest solution.