HOT Fuel, Loud pump and engine buck

[DMC3165]

I have a new problem. Just last week on one of the 90+ degree days i was driving along and out of nowhere the engine had a quick loss of power, like a jolt or buck. At the same time i was chasing a new fuel odor problem. When i got home i had to pull the pump out again. I was surprised to find the the fuel tank was extremely hot! After repairing the leak i started the car to check for leaks. Everything was good but the pump was very noisy and gurgling almost as if it was sucking air. I picked up the pump with the car running ( I know this is dangerous ) to make sure the pickup hose was secure and not sucking air. All was good there. So i took it for a drive and it did the same thing. Everytime I'd go for power the engine would buck a little accompanied by loud gurgling from the fuel pump. So I topped off the tank with fresh gas to cool it down and drove it home. It was fine the rest of the way. I drove it to work and back today. On the way home (about 25 miles in) I noticed it bucked again. When i got home i pulled the access panel in the trunk and again the tank was red hot! So I'm thinking the Hot fuel is killing my pump? It's not a bosch unit, it's one of the imitation brands out there. It was always been a little noisy especially in hotter weather, but now I think it may be on it's way out? Not real sure what to do next. It's only 2 years old with 18000 miles on it. Also the fuel is very hot. This concerns me a little too. It is definitely over 100 degrees in the tank. Not real sure how hot it is but the fact that I can't touch the outside of the tank for too long without it hurting my hand has me a bit unnerved.

Any ideas:dunno:

[Bitsyncmaster]

I have measured fuel temps above 125 deg F in the tank. That is about the time my pump would "buzz".

So far it looks like the DMCH pump/sender has not shown the buzzing. So I would suggest that may be the best option but it's still early in racking up customer run hours.

I installed a cooler for my return gas and have not had the buzz problem since but that was probably more work than anyone else would want to try.

[Michael]

You know I had the same symptoms in hot weather last year. Whenever the tank got hot my car would buck and hesitate and my pump groaned loudly. I immediately replaced the fuel pickup line which did little to help, turned out it was the pump itself. It was replaced last year with one from DMCMW and this year with record temps all is cool with 5609. Even in 100+ degree weather there has never been any noise from the pump.

Everyone probably agrees the pickup line is the most common problem(gets soft and collapses when hot) and of course check the pickup screen, but don't rule out the pump itself.

[Citizen]

I installed a cooler for my return gas and have not had the buzz problem since but that was probably more work than anyone else would want to try.

I sure would like to know more details about how you did this.

Thomas

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[Bitsyncmaster]

I sure would like to know more details about you you did this.

Thomas

...

I had it posted on the old forum. Here are the photos but it's a coil of copper tubing wrapped around the AC accumulator.

[Citizen]

I had it posted on the old forum. Here are the photos but it's a coil of copper tubing wrapped around the AC accumulator.



Was the copper tubing filled with any kind of coolant?

[Bitsyncmaster]

Was the copper tubing filled with any kind of coolant?

The return fuel hose is connected on one end with the other end hosed to the return into the tank. My testing showed the return fuel was always about 2 deg. F higher than the supply (to the FD) fuel. So the engine gives most of that heating to the tank. Everyone seems to think the coolant lines beside the tank heats the fuel.

[Citizen]

The return fuel hose is connected on one end with the other end hosed to the return into the tank. My testing showed the return fuel was always about 2 deg. F higher than the supply (to the FD) fuel. So the engine gives most of that heating to the tank. Everyone seems to think the coolant lines beside the tank heats the fuel.

Interesting!

I have been in the process of designing my own hot-air dam for the front, so to keep the radiator discharge air from heating the fuel tank. Maybe I should abandon that idea, as I had never considered it might me the return fuel heating up the supply.

...

[Bitsyncmaster]

Interesting!

I have been in the process of designing my own hot-air dam for the front, so to keep the radiator discharge air from heating the fuel tank. Maybe I should abandon that idea, as I had never considered it might me the return fuel heating up the supply.

...

I've had John's hot air dam for many years. I don't know if it helps but I had the buzzing problem after it was installed.

[David T]

The coils of copper line around the accumulator is OK but it will reduce the A/C capacity. As for the gurgling, bucking, loss of power, try a spring inside the pick-up hose. The fuel pump creates a very strong suction. When the hose gets that hot even a stiff hose will soften enough for the pump to suck it flat. Once the pump can't move fuel it gets loud and since the fuel also cools and lubricates the pump it will wear it out prematurely.
David Teitelbaum

[DMC3165]

I never liked the idea of the rubber flap air dam but I'm thinking I might give that a try. The amount of heat coming off the fans is unbelievable when the car is at operating temp.

[Morpheus]

I have said this before, but it bears repeating...

In my previous D, I had a hot air dam installed and never had any fuel pump related problems in the FL heat. Mind you, my fuel pump and pickup hose were new @ the time so that may have helped.

If your tank internals need attention anyway, the hot air dam may not solve your problem. However, if you are replacing components already it's another ounce of prevention that may just help keep temps down in the future.

[DMC3165]

I have said this before, but it bears repeating...

In my previous D, I had a hot air dam installed and never had any fuel pump related problems in the FL heat. Mind you, my fuel pump and pickup hose were new @ the time so that may have helped.

If your tank internals need attention anyway, the hot air dam may not solve your problem. However, if you are replacing components already it's another ounce of prevention that may just help keep temps down in the future.

All my tank internals including the baffle are under 2 years old. I may give the flap a try before i pony up the $300 for a Bosch pump. If it's good in Florida heat that's good enough for me.

[DeLorean03]

All my tank internals including the baffle are under 2 years old. I may give the flap a try before i pony up the $300 for a Bosch pump. If it's good in Florida heat that's good enough for me.

When you say "baffle", what exactly do you have for a baffle? I have John's since 2004, and I haven't had any issues.

As far as your pump, I would definitely recommend John's power pump. I really is a Bosch fuel pump, and it is WELL worth it's money at $160. I lived in Pensacola, FL with my car for 9 years, and the 6 years I have had that pump in my fuel system, I have not had any issues - so far.

It's up to you - not telling you to go one way or the other - just recommending what I've experienced with my pump!

[DMC3165]

It's a stock OEM baffle that PJ Grady put in a few years ago. Nothing special. I think the extremely hot weather has just brought this issue to light whereas the pump had been noisy at times before but never had any power issues. I will most likely try the flap fix for now. But summers almost over. Hopefully we'll get a little bit of a break in the weather and maybe this can wait until next year.

[DMC3165]

I spoke with Rob Grady today and he suggested looking at the screen inside the baffle to see if its clogged. This is the first time I heard of this. What do you guys think about this? I'd like to do this inside the tank if I can but I'm not really sure if I can and I'd hate to have to pull the baffle out. Since my symptoms only seem to mainfest when the engine is hot I'm not really sure about a clogged screen in the tank but I'd like some opinions before puling the pump out.......again.

[Morpheus]

There's really no easy way to check that screen without at least removing the pump and tank stud nut and sliding the whole assembly over to the access hole to have a look. You shouldn't have to pull the baffle out of the tank, but still it's a pain.

[whocruiser]

You can count me as another Florida testimonial for the effectiveness of the Hervey/Bauerle rubber mat air dam to keep the hot radiator fan air off of the fuel tank. Had one for 6 or 7 years now on both 1150 and 1662 before it. It was one of the only three things that I actually moved over from the old car to the new one before taking the newer fully refurbed car home from DMC Florida nearly two years ago (the other two being my nice smooth velour grey dash mat, and the coolant auto bleeder plumbing between the thermostat housing bleed point and the overflow bottle.) Years & years of daily driving in SoFla and I'm a very happy camper, wouldn't leave home without either of those two mods in place on my car.

[jawn101]

You can count me as another Florida testimonial for the effectiveness of the Hervey/Bauerle rubber mat air dam to keep the hot radiator fan air off of the fuel tank. Had one for 6 or 7 years now on both 1150 and 1662 before it. It was one of the only three things that I actually moved over from the old car to the new one before taking the newer fully refurbed car home from DMC Florida nearly two years ago (the other two being my nice smooth velour grey dash mat, and the coolant auto bleeder plumbing between the thermostat housing bleed point and the overflow bottle.) Years & years of daily driving in SoFla and I'm a very happy camper, wouldn't leave home without either of those two mods in place on my car.

I've been thinking about the hot air dam for a while, is there more than one vendor selling it currently?

[Gary Weaver II]

I made one for my car last week in about 30 minutes for $8 and change. Used a rubber welcome mat and roughed out the shape using the image off the Special T website. I extended the sides out a little bit more above the front crumple tubes.

It was really easy and made the 45 minute drive on a 106 degree day much easier.

However, the lack of working A/C was a completely different issue :flamed:

-Gary

[jawn101]

I made one for my car last week in about 30 minutes for $8 and change. Used a rubber welcome mat and roughed out the shape using the image off the Special T website. I extended the sides out a little bit more above the front crumple tubes.

It was really easy and made the 45 minute drive on a 106 degree day much easier.

However, the lack of working A/C was a completely different issue :flamed:

-Gary

Interesting. That sounds worth a try! Could make a cardboard template first then cut the rubber to reduce expense and trial/error. Thanks Gary :)

[Citizen]

I never liked the idea of the rubber flap air dam but I'm thinking I might give that a try. The amount of heat coming off the fans is unbelievable when the car is at operating temp.

I plan on fabricating mine out of some type of metal, probably a heavy gauge tin. But not rubber. I think I've got the templates about 90% done.

...

[David T]

My guess is rubber was used because it bends easily can be cut easily and installed easily. If you template up a piece of metal it may not fit other Deloreans well. There is enough variation that a metal one may not fit without some trimming.
David Teitelbaum

[Citizen]

My guess is rubber was used because it bends easily can be cut easily and installed easily. If you template up a piece of metal it may not fit other Deloreans well. There is enough variation that a metal one may not fit without some trimming.
David Teitelbaum

Agreed that it may not fit other DeLoreans. Hadn't really thought about producing more than one, so I was cutting the templates only for my own car. Was going to use a high-grade tin for strength, but still had some flexibility. Aluminum would be too rigid. I guess I'm thinking the rubber would lose its rigidity when it gets hot from the very air it is deflecting. Perhaps even fall away/out of the car, unless secured properly.

I dunno, I'm still in the design/development stage, although I do have my templates just about complete.

...

[DMC3165]

One of the side effects of the rubber flap air deflector is slightly higher water temps due to the restriced airflow behind the radiator (or so I've been told). IMHO if this is true it sounds like solving one problem and creating another one.

I was thinking of putting an air deflector in the front of the fuel tank in between the chassis and the fiberglass tub. Don't know how difficult or practical this might be. But I was thinking of using a heavy piece of poly truck mudflap. They are fairly rigid like a bendable plastic. Just as long as it keeps the hot air from blowing on the tank and it dosen't restrict the air flow behind the radiator it should work. Not real crazy about the idea of something rubbing against my frame or the fiberglass tub but I had this brainstorm last night so I might take a look at this later today.

:t2:

[Morpheus]

One of the side effects of the rubber flap air deflector is slightly higher water temps due to the restriced airflow behind the radiator (or so I've been told). IMHO if this is true it sounds like solving one problem and creating another one.
:t2:

All the air deflector does is channel the air downward under the car and away from the fuel tank. That's it. There is no restricted airflow, it is simply re-directed.

[SS Spoiler]

Go to a farm supply store and ask for wide rubber belting. it's about a foot wide, two ply rubber. Did this 24 years ago, still going strong.

[vwdmc16]

I also need to install a hot air dam. I currently have a remote thermalcouple inside my fuel tank for taking temperature readings . So far my current record is also 125 degrees. my plan to fix the high temperature, is to install a small setrab oil cooler from a volvo, it measures 4 inches by 8 inches, and will fit very nicely next to the radiator on the passenger side.

[jawn101]

I also need to install a hot air dam. I currently have a remote thermalcouple inside my fuel tank for taking temperature readings . So far my current record is also 125 degrees. my plan to fix the high temperature, is to install a small setrab oil cooler from a volvo, it measures 4 inches by 8 inches, and will fit very nicely next to the radiator on the passenger side.

Does this supply store by you have the big rubber belting to make them?

[vwdmc16]

They have piles of urethane mats but they are quite soft, But i bet they would have something, if not perhaps some corrugated plastic, there is a art shop that has big sheets for cheap. Ive used that stuff as radiator ducting on the E21 race car and its never melted or failed.

[DMC5180]

This is all interesting for the Various materials that can be used. But How does it get attached? I recall Rob Grady telling me many years ago he had sourced some clips that would hook over the edges of the frame opening and hold the shield material in place. no drilling required. Does anyone have Robs installation? I'd like to see pictures of it.

[vwdmc16]

My understanding is the bottom is clipped on and the top is kind just wedged in.

[jawn101]

The "clips" that Hervey supplies with his look to be just strips of perforated steel bent into S shapes. Doesn't look that complicated but I'd be worried about them rubbing on the epoxy of the frame. I'm sure we can do better.

[whocruiser]

My understanding is the bottom is clipped on and the top is kind just wedged in.

The inherent shape of the top of the mat simply wedges in pretty snugly with the recesses in the car itself and holds quite snugly. On 1662 I used a section of bendable metal strapping to wrap around the frame and then bent the ends to form a notch that held the bottom of the mat steady. On 1150 I wanted to be more careful of that metal strapping method possibly scraping paint off of the frame members, so this time I punched a couple of holes through the edge of the mat and used plastic zip ties to wrap around the frame instead. Either way it's held just fine. And, as someone else mentioned above, radiator air flow is not blocked or restricted, but simply diverted downward away from the fuel tank area.

[vwdmc16]

After an hour of driving around, mostly in town at 100' ambient temp I reached a new record in fuel temps. 134'F!!!

[Bitsyncmaster]

I attached mine (oneJohn sells) with cable ties.

[Bitsyncmaster]

After an hour of driving around, mostly in town at 100' ambient temp I reached a new record in fuel temps. 134'F!!!

You must have a good pump if it was not buzzing.:rock_on:

[DMC3165]

At the advice of Rob Grady I disassembled my fuel pump and pulled out the baffle. To my surprise my screen was pretty clogged and there was a lot of sediment on the bottom of the tank. The tank floor was cleaned and a new screen and baffle was installed two years ago. So it looks like I'll at least be changing the screen for now. And cleaning the tank again.

[vwdmc16]

You must have a good pump if it was not buzzing.:rock_on:



Thats true!, I have heard it buzz before on a trip to Arizona, it was 109' ambient temp that day and the car had been driving 30hrs straight. i didnt have a temp gauge in the fuel but 140'+ would not surprise me.

[DMC3165]

I decided to pick up a hot air dam from Gradys when I bought my new fuel pickup screen the other day. I must say both have worked extremely well. My fuel pump makes absolutely zero noise at all now. Even with only 1/4 tank of gas and the outside temp at 90 degress and my A/C on. The heavy rubber flap was a bit of a pain to get in place and Grady gave me trailing arm cover clips to mount it with. Those were equally as stubborn to put in place but all in all I'm happy with the results. Guess I won't be needing a new fuel pump after all. :yesss:

[jawn101]

I decided to pick up a hot air dam from Gradys when I bought my new fuel pickup screen the other day. I must say both have worked extremely well. My fuel pump makes absolutely zero noise at all now. Even with only 1/4 tank of gas and the outside temp at 90 degress and my A/C on. The heavy rubber flap was a bit of a pain to get in place and Grady gave me trailing arm cover clips to mount it with. Those were equally as stubborn to put in place but all in all I'm happy with the results. Guess I won't be needing a new fuel pump after all. :yesss:

How much was Grady's hot air dam out of curiosity?

[DMC3165]

How much was Grady's hot air dam out of curiosity?

Sorry for the delay in getting back. It was $25. However he only had two left and they had both been laying around for a while. I'm not real sure if he's planning on getting more or not but I know there's definetly one left.

[DMC3165]

Sorry Dennis there was no real good way to take a pic of this but here's the best I could do....you get the idea

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