Fuel pump failures

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Originally Posted by dvfr750f

So I have John herveys pump kit with the 'tuna can'. I tend to go thru pumps in the summer so heat is the culprit, but how?
Here is what I think.

I am getting 12.46 v at the pump when under load. The RPM relay is functioning and looks clean, but does have a slightly burnt odor to it. It does get quite hot while driving. Anyone know what the normal op temp is for this?
I bought a new pump from DMC(looks identical to Herveys pump). I installed it and after about 30 min in city traffic on a 90 deg day it began to cavitate.
I pulled over checked the fuel by removing the send unit and just sticking a finger in. The fuel didnt feel very hot. The water temp was mid way from btm to the 220 mark. I then placed a bag of ice right ontop of the fuel lines and the pump(top), let her sit for an hour then drove home. I managed to make it the 10 miles home. The pump screamed the whole way.
SOOOO, I believe it is a heat problem but not an electrical one.
I recently overhauled the entire cooling system to include a new radiator and elec fans. Before this, one of the original fans was not functioning so now the car is pulling ALOT more heat from the radiator and sending that heated air right over the tank and superheating the fuel lines and the top of the pump. I also am getting a fuel odor in the cabin. I suspect that this is the problem.
Today I fabricated an air dam out of thin sheet metal and this has removed ALL air from the radiator to being pushed over the tank. I also put a foam insulation over the two fuel lines. I will drive tomorrow and see how she performs.

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I just can't believe you have had 2 pumps go bad in such a short period of time. Are you sure there is not a crack or tear in the pick-up making the pump suck air? Are you sure you are orientating the pump and boot correctly so the pick-up is not getting kinked? I have had my DMC pump out in 100+ temp traffic and it doesn't even make noise.

Quote:

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Originally Posted by dvfr750f

So I have John herveys pump kit with the 'tuna can'. I tend to go thru pumps in the summer so heat is the culprit, but how?
Here is what I think.

I am getting 12.46 v at the pump when under load. The RPM relay is functioning and looks clean, but does have a slightly burnt odor to it. It does get quite hot while driving. Anyone know what the normal op temp is for this?
I bought a new pump from DMC(looks identical to Herveys pump). I installed it and after about 30 min in city traffic on a 90 deg day it began to cavitate.
I pulled over checked the fuel by removing the send unit and just sticking a finger in. The fuel didnt feel very hot. The water temp was mid way from btm to the 220 mark. I then placed a bag of ice right ontop of the fuel lines and the pump(top), let her sit for an hour then drove home. I managed to make it the 10 miles home. The pump screamed the whole way.
SOOOO, I believe it is a heat problem but not an electrical one.
I recently overhauled the entire cooling system to include a new radiator and elec fans. Before this, one of the original fans was not functioning so now the car is pulling ALOT more heat from the radiator and sending that heated air right over the tank and superheating the fuel lines and the top of the pump. I also am getting a fuel odor in the cabin. I suspect that this is the problem.
Today I fabricated an air dam out of thin sheet metal and this has removed ALL air from the radiator to being pushed over the tank. I also put a foam insulation over the two fuel lines. I will drive tomorrow and see how she performs.

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The OEM RPM relay will get very hot inside. How hot it feels on the outside case depends how long you have been running.

I've found when the fuel gets > 120 deg. F. the pump will start making noise. So check your fuel temp in the tank and see if it's that hot.

After reading through this thread you are having the exact same problems I had. Mine turned out to be a clogged pickup screen in the fuel tank. It clogged AFTER I cleaned the tank. Then it did it again a year later. Rubber was getting in the tank through the return from a disintegrating fuel line. Disassemble your baffle and check your pickup screen. If it's black change it. It think it's around $15.

Thanks for all the feedback. The fuel and the screen are all very clean. After,considerable evaluation and driving the car(with air dam installed), i believe the problem is a direct result of radiator fans blowinghot air OVER the pump and the lines. Not so much the temp inside the tank(although it does contribute). With the fix, i have no air flowing over the pump and temps are hugely reduced!

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Originally Posted by jorge figueroa

you should use the same product used in the exhaust headers as
cover the cooling tubes in the fuel tank area
controlling the transfer of heat between the cooling tubes and the gas tank
so the fuel pump is not affected by heat and the engine will have better performance
Heat is the horsepower and performance killer.


http://www.thermotec.com/products/11...ader-wrap.html

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Finally the solution to the problem of overheating of the pump and the gasoline tank in deloreans.
Many deloreans including mine have always had this problem of having the gas pump very hot when you make a long trip around Puerto Rico. And in some cases total failure.
The problem arises from the poor design of the delorean cooling system.
Especially the tubes that pass under the gas tank. These tubes are heated by the coolant that comes from the engine to the radiator, heating the tank, gasoline and the pump to temperatures too high for its proper functioning.
As a result you hear a loud buzzing inside the car (pump too hot) and the possibility of failure.

For some time I was looking for a solution to this problem, and finally found in home depot a type of tape that is used to insulate tubes in the air conditioning system of homes or businesses. (To see photos).
It is an aluminum tape with high density foam insulation.
Using my own delorean I did heat transfer tests with one of the cooling system tubes and found that the heat transfer is practically zero.
With my delorean engine running I put my hand on the coolant pipe with the insulation and felt no heat at all.
If my hand did not feel any heat the tanks of the deloreans either

Attachment 59079Attachment 59080Attachment 59081Attachment 59082

Quote:

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Originally Posted by jorge figueroa

Finally the solution to the problem of overheating of the pump and the gasoline tank in deloreans.
Many deloreans including mine have always had this problem of having the gas pump very hot when you make a long trip around Puerto Rico. And in some cases total failure.
The problem arises from the poor design of the delorean cooling system.
Especially the tubes that pass under the gas tank. These tubes are heated by the coolant that comes from the engine to the radiator, heating the tank, gasoline and the pump to temperatures too high for its proper functioning.
As a result you hear a loud buzzing inside the car (pump too hot) and the possibility of failure.

For some time I was looking for a solution to this problem, and finally found in home depot a type of tape that is used to insulate tubes in the air conditioning system of homes or businesses. (To see photos).
It is an aluminum tape with high density foam insulation.
Using my own delorean I did heat transfer tests with one of the cooling system tubes and found that the heat transfer is practically zero.
With my delorean engine running I put my hand on the coolant pipe with the insulation and felt no heat at all.
If my hand did not feel any heat the tanks of the deloreans either

Attachment 59079Attachment 59080Attachment 59081Attachment 59082

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Very nice. I admit on hot days and long drives with the A/C on, my pump makes noise and something I would like to address. It's a shame you have to drop the tank to install though :(

Looks like a great idea but how do you get the tank back in without tearing off the insulation? Would it be better to just insulate the pipes?

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Originally Posted by David T

Looks like a great idea but how do you get the tank back in without tearing off the insulation? Would it be better to just insulate the pipes?

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It would be nice if you could slide some insulation between the tank and pipes without removing anything, but one side being adhesive might pose a problem.

I bought a custom bellypan for my motorcycle and let me tell you after installation, it was about 1/4" away from some very hot exhaust pipes. After just a few minutes, the painted surface would almsot burn your hand. I knew it would melt the plastic let alone blister the paint. I got some adhesive thermo liner and now it is cool to the touch even after sitting idling. Never thought something like that would work and it so happens I have plenty left over.

https://www.amazon.com/Thermo-Tec-14...vglnk-c1044-20

You can see just how close the exhaust pipe runs, they even made cutouts in the bottom, yet after installation of that thermo sheet, not a problem.

Attachment 59087Attachment 59088

I do hope that fixes your problem. But I did some testing and I think a major cause of the gas heating is the return fuel line. The excess fuel runs to the hot engine and is returned to the tank. I measured the heat gain from the two tank lines and the return was 1 to 2 degrees F warmer then the feed line.

Hi!
I hope my input is not too much off-topic, but as I am restoring my DeLorean #1550, which was imported 4 years ago from NY to Germany, my (original BOSCH) fuel pump changed its speed nearly every second, I bought a new one from John Herveys DAP-site just one week ago. As I read here, some people are not convinced about the fuel pumps sold on the DAP-site!? Mine did not yet arrive, but as I read this thread I´m not sure if I did the right thing...
I did not buy the one with the strange can-like baffle, but the one which is one solid module, similar to the new design offered from DMCH, but less plastic...
I would be very happy to hear, which experiences you made with THAT pump.
I hope I will not step on someones feet with this message...
Thank you, Lars.