Hot start problem

[homeselljeff]

I was at a show today for 4 hours and had trouble starting , the starter turns over fine the battery almost died before it started then when I got home I shut it down and it started right up until it sat for about 5 hours then it was hard to start again
Any ideas?
Thanks


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[DMCMW Dave]

I was at a show today for 4 hours and had trouble starting , the starter turns over fine the battery almost died before it started then when I got home I shut it down and it started right up until it sat for about 5 hours then it was hard to start again
Any ideas?
Thanks


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Fuel Accumulator
Fuel Pump Check Valve
Distant third - Fuel distributor pressure o-ring.

Here is a more detailed article: http://support.delorean.com/kb/a61/hot-start-issues.aspx


Do you know the maintenance history on these items?

[homeselljeff]

I don't know too much about the history where should I start?


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[homeselljeff]

What are the symptoms of the fuel accumulator?


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[DMCMW Dave]

I don't know too much about the history where should I start?

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Look in the glove box.

heh. l couldn't resist.

I'd change the accumulator first unless it looks new.

[homeselljeff]

Ok I'll start there where is the best place to order it?


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[DMCMW Dave]

Ok I'll start there where is the best place to order it?


Well - I'm partial to DMC Midwest since I still work there, but I don't know where you live. I'd hate to say order it here if you happen to live in Florida for example. Any vendor will have it.

[homeselljeff]

I'm in Va. Near Charlottesville 1 hour from Richmond


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[David T]

Any Delorean vendor can help you. Ask for the original style "long" one and you may need to replace the hoses to it while you are in there. Take great care not to do ANY damage to the fittings or the hard lines. If you do you will have to lift the body to replace them! Before replacing the accumulator there is a test to verify if you are losing rest pressure causing the hard hot restart. When it is hot and won't start, switch the plugs on the cold start valve with the control pressure regulator. Switch them back IMMEDIATELY once it starts. If the plug swap works go ahead and change the fuel accumulator.

[axh174]

I was at a show today for 4 hours and had trouble starting , the starter turns over fine the battery almost died before it started then when I got home I shut it down and it started right up until it sat for about 5 hours then it was hard to start again
Any ideas?
Thanks


I'm going to ask what may be a silly question just to make sure we're all on the same page. You had the car running, you were able to shut it down and immediately start it up without any issue, but after you let it sit for 5 hours it was hard to start?

That sounds like a cold-start issue, not a hot-start.

Are the remedies the same?

[David T]

You have to let the pressure drop a little so even with a bad accumulator it would start up immediately because you would still have some rest pressure. The problem is more like if you stopped for some gas and then went to restart it after about 5 minutes. Once you get a hard hot restart it won't start again till either you do the plug swap or you wait til it cools enough for the Cold Start Valve to run off of the TTS. Depending on the ambient temperatures it can take a long time to cool down enough in the hot summertime with the car sitting in the hot sun.

[axh174]

You have to let the pressure drop a little so even with a bad accumulator it would start up immediately because you would still have some rest pressure. The problem is more like if you stopped for some gas and then went to restart it after about 5 minutes. Once you get a hard hot restart it won't start again till either you do the plug swap or you wait til it cools enough for the Cold Start Valve to run off of the TTS. Depending on the ambient temperatures it can take a long time to cool down enough in the hot summertime with the car sitting in the hot sun.

Dave, thanks for the clarification. I wasn't aware the hot-start issue could be somewhat time-dependent. When I had a hot-start problem, I could not restart the car even if I turned it off and on immediately. The problem went away after I replaced the PPR O-ring. I just assumed a hot-start problem meant an immediate no-start under hot conditions.

[Ron]

Dave, thanks for the clarification. I wasn't aware the hot-start issue could be somewhat time-dependent. When I had a hot-start problem, I could not restart the car even if I turned it off and on immediately. The problem went away after I replaced the PPR O-ring. I just assumed a hot-start problem meant an immediate no-start under hot conditions.Yeah I had a "upgrade" in mind
for this that is right down your alley :devil:.
Tap the YR wire (hot only when running) at the ECU, flip the signal, and send it to the CSV. It wouldn't interfere with normal operations and would help with very cold starts as well as hot starts -- A poor man's spray pump lol.
Of course Dave's new style RPM relay takes care of the cold start-accumulator part.

[homeselljeff]

I think you are right it should be cool within a few hours I just warmed up the car ran it in the garage for about 15 minutes and the fans didn't come on the temp went just above the first mark. When I had the start problem I turned off the battery switch I'm not sure if cutting the power course a start problem I


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[homeselljeff]

I also opened the cover over the brake fluid and there was a loose ground and a connector on top of the brake fluid cap wasn't hooked up so I reconnected them both


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[DMCVegas]

Dave, thanks for the clarification. I wasn't aware the hot-start issue could be somewhat time-dependent. When I had a hot-start problem, I could not restart the car even if I turned it off and on immediately. The problem went away after I replaced the PPR O-ring. I just assumed a hot-start problem meant an immediate no-start under hot conditions.

The Hot Start issue is caused by fuel pressure bleeding-off. K-Jetronic is a hydraulically operated system where you need to build-up fuel pressure to crack open and control the injectors. EFI of course will work under any fuel pressure because the injectors are electronically controlled. So when the pressure is low on a cold engine, the Thermo-Time Switch is triggered, and the Cold Start Valve pops-open to crudely carburete the engine to get it running (albeit roughly) for a few seconds while the fuel pump re-pressurizes the fuel system and cracks the injectors back open to take over responsibility of fuel delivery.

When the engine is hot and the system bleeds out, the TTS never gets tripped, so the CSV doesn't spray, and then you get the hot start condition where you have to wait for the engine to cool down for several hours to restart it without external intervention.

A cold start problem is where the CSV never sprays at all to create the "choke" enrichment and the engine will not start when cold, which happens after several hours.

Any kind of starting issues like this should be troubleshot and repaired properly and accordingly instead of just throwing money/parts at the car.

The PPR O-Ring under normal circumstances I agree is a VERY distant third. UNLESS you've been trying to tamper with some mechanic in a bottle fuel additive, or ran any gasoline with more than a 15% dilution rate of ethanol (like E-85). I can tell you now that anything stronger than a bottle of Techron should never be used because of the rubber in the system. I tried Berryman B-12 and even straight denatured alcohol to try and "clean" my engine/injectors, and it ate up that O-Ring in no time at all. Like you I replaced it, and as soon as it was back on, the car ceased to have any problems.

If you're having a hot-start issue, the most discrete way to temporarily address it is to click your ignition key to the "ON" position. Do NOT start the engine! Just click the key forward. That will energize the RPM Relay which will intermittently run the fuel pump for a few seconds, but not drain power from your battery. Then click the key back to turn the engine off and repeat. You will need to do this several times in succession, but you will get the fuel system back up for a quick start.

Also, make sure that you depress the gas pedal down ¼ of the way while cranking your engine. It's apart of the starting directions in your Owner's Manual, and I can attest that it indeed DOES make a difference in easier starting.

[Michael]

The Hot Start issue is caused by fuel pressure bleeding-off. K-Jetronic is a hydraulically operated system where you need to build-up fuel pressure to crack open and control the injectors. EFI of course will work under any fuel pressure because the injectors are electronically controlled. So when the pressure is low on a cold engine, the Thermo-Time Switch is triggered, and the Cold Start Valve pops-open to crudely carburete the engine to get it running (albeit roughly) for a few seconds while the fuel pump re-pressurizes the fuel system and cracks the injectors back open to take over responsibility of fuel delivery.

When the engine is hot and the system bleeds out, the TTS never gets tripped, so the CSV doesn't spray, and then you get the hot start condition where you have to wait for the engine to cool down for several hours to restart it without external intervention.

A cold start problem is where the CSV never sprays at all to create the "choke" enrichment and the engine will not start when cold, which happens after several hours.

Any kind of starting issues like this should be troubleshot and repaired properly and accordingly instead of just throwing money/parts at the car.

The PPR O-Ring under normal circumstances I agree is a VERY distant third. UNLESS you've been trying to tamper with some mechanic in a bottle fuel additive, or ran any gasoline with more than a 15% dilution rate of ethanol (like E-85). I can tell you now that anything stronger than a bottle of Techron should never be used because of the rubber in the system. I tried Berryman B-12 and even straight denatured alcohol to try and "clean" my engine/injectors, and it ate up that O-Ring in no time at all. Like you I replaced it, and as soon as it was back on, the car ceased to have any problems.

If you're having a hot-start issue, the most discrete way to temporarily address it is to click your ignition key to the "ON" position. Do NOT start the engine! Just click the key forward. That will energize the RPM Relay which will intermittently run the fuel pump for a few seconds, but not drain power from your battery. Then click the key back to turn the engine off and repeat. You will need to do this several times in succession, but you will get the fuel system back up for a quick start.

Also, make sure that you depress the gas pedal down ¼ of the way while cranking your engine. It's apart of the starting directions in your Owner's Manual, and I can attest that it indeed DOES make a difference in easier starting.

I could be wrong but I didn't think the fuel pump energized unless the starter was turning....unless you have one of Dave's rpm relays.

[Bitsyncmaster]

Some stock RPM relays will prime the system for one second when the key goes on.

You can prime all you want but that will not cure the hot start problem. The problem is vapor gets in the injector lines and then the fuel distributor can not get the 40 PSI to open the injectors. If you can get the engine firing with the CSV (plug swap), that can open the distributor air plate wider than the starter cranking and push more fuel into the injector lines.

[axh174]

and then you get the hot start condition where you have to wait for the engine to cool down for several hours to restart it without external intervention.

Hmmm interesting. So with regards to the OP, would 5 hours suffice as sufficient time to cool down and try to restart?


The PPR O-Ring under normal circumstances I agree is a VERY distant third.

I would normally agree with this. While my experience is limited enough that I can't argue it's not true, in my case it was the primary problem. And I wasn't any using any fuel additives or cleaners. This is pretty typical of my luck, though (the old .com site had the story of my automatic shift computer where I found out the problem with it was a manufacturing flaw in the molded block top that resulted in an internal short. To my knowledge, I'm still the only one who has had this kind of problem). I first replaced my fuel accumulator with a brand new "original-longer" style that I got off of Amazon after specifically searching for the part number. This didn't solve the problem and I pressure tested my old accumulator only to find out it was still good. Next, I inserted a reverse-flow check-valve in the main feed line right off of the fuel pump. I figured it'd be nice to have a back-up check valve if the one in the pump was still good. Turns out the one in the pump was still good. Lastly I replaced my PPR O-ring and that did the trick. The upside to all this work is the fuel system is pretty rock-solid now. =)


If you're having a hot-start issue, the most discrete way to temporarily address it is to click your ignition key to the "ON" position. Do NOT start the engine! Just click the key forward. That will energize the RPM Relay which will intermittently run the fuel pump for a few seconds, but not drain power from your battery. Then click the key back to turn the engine off and repeat.

Given what Dave said, this would make sense. If your system is slowly bleeding off pressure, then priming the pump enough might get the system back up to start the engine. With my PPR O-ring shot, though, the system couldn't maintain any sort of rest pressure. So even with priming the system like this I couldn't get the car started.


Also, make sure that you depress the gas pedal down ¼ of the way while cranking your engine. It's apart of the starting directions in your Owner's Manual, and I can attest that it indeed DOES make a difference in easier starting.

+1

[Bitsyncmaster]

My experience.

A bad accumulator will not hold rest pressure for much more than 5 minuets.

An O-ring with a chip in it can cause loss of rest pressure. The chipped O-rings seem to not show up anymore so I think it was a lot of faulty O-rings.

My car would hold rest pressure for two hours. If I tried to start it at three hours it would not start but at four hours it would. That is why I designed my RPM relay to extend rest pressure another 3 hours by priming the system every hour for three times after engine shutdown. Two other owners also had that same "warm start" problem.

My Hot start relay will run the CSV on a hot or cold engine but only becomes active after one second of engine cranking. So with it installed you don't have to do the "plug swap" but I still recommend you fix a rest pressure problem. It also can let you remove the thermal time switch which I have done.

[steve6864]

Speaking of the hard lines,I feel I might have damaged mine in fitting a new accumulator. The flex line heading up into the body kinked a little at the fitting.Is there access to that fitting? Also,I wished I had known there was a choice because I would have definetaly asked for a "long' original type. The short one DMC Houston sent me doesn`t reach the whole bracket used to hold it up and the long rubber hose to extend it that comes with the kit was a joke. Anyway if anybody sees a Delorean on the side of the road heading to Springfield it`s probably me with fuel accumulator leaks.

[Michael]

The accumulator that the DMC vendors use now is for a 4 cyl. engine(which is why the hose is oncluded to fit the bracket) because supposedly the 6cyl OE part is NLA but I have heard that it is readily avaliable from other sources.

[Morpheus]

I'll just leave this here:

https://www.amazon.com/Bosch-438170029-Fuel-Pressure-Accumulator/dp/B001CO6GJ2/ref=sr_1_1?ie=UTF8&qid=1469019156&sr=8-1&keywords=Bosch+438170029+Fuel+Pressure+Accumulator

[DMCVegas]

I could be wrong but I didn't think the fuel pump energized unless the starter was turning....unless you have one of Dave's rpm relays.

Nope. The W/S or White/Slate wire is the RPM feed from the engine. This feeds among other things the Tachnometer and the RPM Relay. The relay itself includes a 555 Timer Chip. So when you click the key over to "ON", the RPM relay is energized and starts intermittently powering the Fuel Pump for a couple of seconds. Once it gets a steady RPM signal the relay remains tripped to continuously power the Fuel Pump.

If the car does not start, or whenever the engine stalls, the RPM signal is not present and the Relay automatically kills power to the Fuel Pump. But as long as there is a pulse signal, the Relay remains constantly energized.



Hmmm interesting. So with regards to the OP, would 5 hours suffice as sufficient time to cool down and try to restart?

5 hours would be more than enough cool-down time for most places, yes. The exception being desert environments.



I would normally agree with this. While my experience is limited enough that I can't argue it's not true, in my case it was the primary problem. And I wasn't any using any fuel additives or cleaners. This is pretty typical of my luck, though (the old .com site had the story of my automatic shift computer where I found out the problem with it was a manufacturing flaw in the molded block top that resulted in an internal short. To my knowledge, I'm still the only one who has had this kind of problem). I first replaced my fuel accumulator with a brand new "original-longer" style that I got off of Amazon after specifically searching for the part number. This didn't solve the problem and I pressure tested my old accumulator only to find out it was still good. Next, I inserted a reverse-flow check-valve in the main feed line right off of the fuel pump. I figured it'd be nice to have a back-up check valve if the one in the pump was still good. Turns out the one in the pump was still good. Lastly I replaced my PPR O-ring and that did the trick. The upside to all this work is the fuel system is pretty rock-solid now. =)

Well, there is some clarification needed here. There are indeed some variables here. In the case of a bad PPR O-Ring, you've got a leak far enough down the system that you can refill a significant portion of fuel back into the system. With a bad check valve, you're only needing to refill a much smaller section of the fuel system. With a bad accumulator, you've got a whole lot more of the fuel system that has been drained and needs to be refilled.

Dave IS correct that simply priming the system like I recommended will not make the Hot Start issue go away, and yes, it is because of the vapors in the line (though please do NOT confuse this with Vapor lock. Totally different issue that doesn't apply to fuel injection, nor most late-model carburetor engines). Vapors/gas/non-liquid in the lines compress and don't fully allow the system to prime & pressurize.

HOWEVER, the idea of a partial prime like I am recommending will at least refill SOME of the missing fuel inside of the system. This will allow it to reach the CSV quicker in order to keep the engine going long enough for the Fuel Distributor to purge the vapors out through the return line into the fuel tank for less battery cranking.

Speaking directly of the PPR O-Ring, running additive chemicals will exacerbate the problem to be sure, but the real problem is Ethanol. It's terrible on rubber.



Given what Dave said, this would make sense. If your system is slowly bleeding off pressure, then priming the pump enough might get the system back up to start the engine. With my PPR O-ring shot, though, the system couldn't maintain any sort of rest pressure. So even with priming the system like this I couldn't get the car started.

It's not a full prime, and I've even had to do it for a few minutes to get the car going. But again it's simply to get enough fuel into the system for a shorter cranking time, not to resolve the problem entirely.

[Bitsyncmaster]

For anyone interesting in testing new fixes for a hot start problem, you can dump rest pressure after your engine is hot via jumping the double yellow/red wires on the RPM relay socket to 12 volts. It takes about 60 seconds to dump all the rest pressure. You will hear the FV buzz change frequency when the pressure is gone. I do that if I need to work on fuel lines to dump the rest pressure.

[GS450-Junkie]

So I've done some reading on here this morning about fuel accumulators. Most that are bad are typically not holding pressure after the engine is turned off and have to be replaced. I have sort of a different problem but I don't see many posts on here discussing an actual physical leak of the accumulator itself. I've had a fuel puddle under the car, and I know it's coming from the accumulator. I finally crawled under the car to have a look and quickly noticed that the rear hose was actually weather-checked and cracked rather badly, not to mention that one end of the hose was wet. I changed it out. It was a pain, but I got it done. (Let me just mention to anyone who hasn't done this before...that you don't necessarily want to use "hose" clamps to secure these hoses, especially if you found these hose clamps in a tired old hardware drawer down in your basement. Take the time to go to your favorite auto parts store and get some "fuel injection line" clamps instead...they tighten much better and you may save some time if you skip the first ones). Anywho, figured my problem would be gone. Nope. Still dripping. This time I started the car, and laid under it while it was running (this is a little scary BTW). I took off the accumulator clamp so I could move it around and check the other hoses. I assumed it must be the other flex line that disappears up onto one of the hardlines. Nope, all 3 hoses and connections were dry. Still dripping (at this point onto my head). It's dripping from the center of the accumulator where the 2 halves meet. I wipe it clean with a rag and in about 3-8 seconds a small pool of fuel begins to form right in the middle again. Pool turns into a drip, and repeats. Has anyone else experienced this? I'm thinking this was replaced in 2007 when I had a major overhaul of the fuel system done at DMCMW. Probably around 2,500 miles since. (Just mentioning this to anyone who is a statistician LOL).

I'm going to attempt to find one of these things locally. Not sure if that is even possible since I only see a few posts about ordering them from Amazon or DMCH.

My fuel looked yellow. Indeed so yellow that I originally spotted the puddle and thought it was coolant. I began checking the coolant lines that run under the accumulator but have indeed verified that it is the accumulator itself. So.... with gas that disgusting I cleaned my tank and put in the new pump/sender combo "while I was in there." Seems like a nice setup, but I'm also reading about failure rates on that as well so we'll see. I don't like DMCH's warranty that it came with. 6 months from date of purchase. It should be a mileage thing instead. Like say 2,000 miles or whatever. I realize that is harder to proove on paper and they'd probably take a hit with people fudging numbers to get it replaced, but I just bought one in November....I'm in Wisconsin.....Car goes into storage until April.... when I wake it up next year the warranty will be expired. Oh well I guess, poor planning on my part.

Anyway.... Once I cleaned the tank and installed everything back together again.... my fuel drip returned but it was much cleaner looking fuel. :) Anyone else have a leaky accumulator? I assumed it was one solid piece?

[Michael]

It could be the accumulator or it could be above it. There are hard fuel lines just above and around the accumulator and the only way to access them is to remove the center console and go in through the top (there is a removable cover on the underbody). You may have a compression fitting loose.

[David T]

You aren't accessing anything from the top. Get under the car and inspect the area while running the fuel pump. If the accumulator is leaking replace it again. If one of the connections above is leaking then tighten it up. They are steel fittings so you have to really crank on them to get them sealed.

[Michael]

You aren't accessing anything from the top. Get under the car and inspect the area while running the fuel pump. If the accumulator is leaking replace it again. If one of the connections above is leaking then tighten it up. They are steel fittings so you have to really crank on them to get them sealed.

Not only was I able to tighten a leaking fuel fitting from the top, but I was able to identify which one I needed to tighten...so yes you can indeed access it from the top.