Weird fuel pump problem… Dual Bosch 044 pumps

Turbo308 · 11-02-2009, 01:15 PM

I am having a really weird fuel pump problem… I am currently running dual Bosch 044 fuel pumps… The other day I noticed the fuel pumps making some funny noises.. Fuel pressure was moving and my A/F was leaning out.. Got it home and noticed that one of the pumps was not getting power (I may have been running on 1 pump for a while)… well today the car lost all fuel pressure while driving.. it stalled and I pulled over.. went back checked the relays.. and everything seemed fine (nothing lose and the pumps didn't seem to be to hot.. but the relays were really warm!) well the car started up and fuel pressure once again dropped and the car stalled… well I pulled one of the relays so only one pump was running… and it built pressure and drove it home… I got home and put both relays back in and went driving… about 30 minutes into the drive it did it again.. I pulled the same relay and it worked and got me home… WTF!?

When I got home I put both relays back in and fuel pressure held steady... its almost like its when they get warm or something…

So do you think that one pump is done?.. how can I test it?.. is there a certain voltage they are supposed to get?.. any help would be much appreciated!.. I also put new relays in after the first deal.. Does this sound electrical?..

huafist · 11-03-2009, 12:00 PM

What happens if you pull the other relay when it happens instead of the one you've been pulling? I don't see how one pump being bad could cause the other one to not even come on unless it was shorting, and that would cause them both to overheat.

jrtech · 11-03-2009, 01:21 PM

What is the relay's amperage capacity?

I mean you have a separate relay for each so this shouldn't be a problem, unless the pump is going bad and dragging causing excessive draw...

Turbo308 · 11-03-2009, 01:52 PM

They are 30 amp relays... One person mentioned to bypass the relays to rule them out.. so I need to try that.. the only problem is I have to drive the car in order for the problem to happen and I really don't want to get stranded if it decides to completely go out..

jrtech · 11-03-2009, 02:25 PM

Hehe, that's the only way to find out... bring an extra pump.

Oooh something also came to mind. As a diagnostic aid, you can bump the pump/relay when it quits and also reverse polarity briefly to dislodge a stuck pump.

Turbo308 · 11-03-2009, 04:48 PM

Quote:

Oooh something also came to mind. As a diagnostic aid, you can bump the pump/relay when it quits and also reverse polarity briefly to dislodge a stuck pump.

What do you mean reverse the polarity?.. do you mean switch 12v key hot with the acc. on the relay (86 & 87) and what do you mean by dislodge a stuck pump?...

jrtech · 11-03-2009, 08:21 PM

Reversing polarity, meaning run the pump in reverse of normal flow by swapping + and - leads. That only works if there is a gritty chunk stuck in there and it is hung up.

I should have clarified, it was just an afterthought for when/if you have it happen again and get stranded.

Turbo308 · 11-05-2009, 11:24 PM

So today I hard wired the pumps (from the relay base I jumped 30 and 87 12v straight to the pump) which took out all the relays in the system and drove it… well not one problem all day!... drove a good 50-60 miles.. to work etc etc… well on my way home tonight.. guess what.. I start to here the pumps making noise again… and then it lost fuel pressure and the car died… I pulled over and pulled one of the jumpers… and I could not get the pumps to prime (I tried both pumps and one at a time) … I tried for about 10 minutes and it would not get above like 10 psi of pressure… and then out of no where it decided to prime and start up (I only had one relay in … so only one pump which was the same relay that worked for me the other day)… drove it half way home and decided to switch the relays to see if it was really the other pump… drove home fine… WTF?!?!?!?!?!?... Are both pumps going out?.. Am I just losing prime because of cavitation??.. I also opened the fuel door and there was no pressure..
Someone help here?!?!...

jrtech · 11-06-2009, 10:34 AM

Quote:

Originally Posted by Turbo308

So today I hard wired the pumps (...) and I could not get the pumps to prime (I tried both pumps and one at a time) … I tried for about 10 minutes and it would not get above like 10 psi of pressure… and then out of no where it decided to prime and start up (I only had one relay in … so only one pump which was the same relay that worked for me the other day)… drove it half way home and decided to switch the relays to see if it was really the other pump… drove home fine… WTF?!?!?!?!?!?... Are both pumps going out?.. Am I just losing prime because of cavitation??.. I also opened the fuel door and there was no pressure..

This is progress! The symptom APPEARS to be a case of a worn-out fuel pump. However unlikely, both failing simultaneously is a possible scenario so let's not rule it out.
Don't assume that your circuit is sound, check the integrity of connections, +, -, switching device, fuse/circuit breaker, etc. before you go throwing two pumps at the problem.
Another possibility is the pickup is blocked by something. More information about your system design would be helpful to see some failure modes.

Turbo308 · 11-06-2009, 11:40 AM

I have thought about a blockage and was going to yank the fuel filter off and clean it out... It just seems to me that one pump was much louder than the other (I put it on a lift and listened while it was running)... I am thinking one pump is going out... but why would I not prime.. because when it is cold I can prime the car with one pump fine... I checked all the connections to the pumps and they seemed to be good... and since I jumped the relay bases the only wiring would be from the base to the pump and from the base to the battery (as well as grounds of course)...

Here is a quick picutre of the setup (the only thing that has changed is the -8 going in and out of the pumps are much shorter for clearence purposes)..

Turbo308 · 11-06-2009, 11:41 AM

And the tank is sumped.. so no pickup..

jrtech · 11-06-2009, 08:30 PM

I'm satisfied with the diag. if you are. All signs (noise, intermittent failure, low pressure) point to pumps.

BUMP FOR SECOND OPINION

Turbo308 · 11-07-2009, 12:08 AM

Well I think I found the problem!!... I had my tail pipes welded up a few weeks back… Well he was next to the gas tank and did not want to get sparks in the tank so he put a GOLF TEE in my vent tube and forgot to take it out!!.. I am 99 percent sure that is what the problem was!... It was not the pumps or the damn relays… the whole time it was not cooling the pumps or the relays it was cooling the fuel from cavitating… Crazy!..

jrtech · 11-07-2009, 10:15 AM

Turbo308 · 11-07-2009, 10:58 AM

Quote:

Originally Posted by jrtech

Tell me about it!.. Thanks for all your help though!

Turbo308 · 11-07-2009, 09:45 PM

Well.. I went driving the car today.. all day was good... until..... It did it again... did great all day (a good 50 miles just driving around)... then out of know where the fuel pressure just dropped off... would not start... and I pulled both relays and jumped them.. and I did one at a time and the most it would see is about 10 pounds of fuel pressure... then after about 5-10 minutes it built pressure (this time with both relays in) and drove a good ways back home with no problems!!! So... back to square one!! DAMNIT!!!... So back up top for some help… Is this just two bad pumps?!!?!... Do I need to put one pump on a hobs switch and only run one pump until boost comes on?..

jrtech · 11-08-2009, 01:38 AM

Quote:

Originally Posted by Turbo308

Well.. I went driving the car today.. all day was good... until..... It did it again... did great all day (a good 50 miles just driving around)... then out of know where the fuel pressure just dropped off... would not start... and I pulled both relays and jumped them.. and I did one at a time and the most it would see is about 10 pounds of fuel pressure... then after about 5-10 minutes it built pressure (this time with both relays in) and drove a good ways back home with no problems!!! So... back to square one!! DAMNIT!!!... So back up top for some help… Is this just two bad pumps?!!?!... Do I need to put one pump on a hobs switch and only run one pump until boost comes on?..

Did you notice a vacuum when you pulled the fuel cap during the period the golf tee was sabotaging you? That's a cause for failure. You already know that pumps do not endure cavitation. If you have bad pumps, you have succeeded in finding the root cause.

To rule out any remaining blockage causing vacuum on the tank, next time failure happens, remove the gas cap then check if fuel pressure comes back.

It's interesting because you mention the same period of time in which the pumps will make pressure, which brings to mind maybe it's related to vacuum accumulating in the tank, and subsiding during the period of time after failure.

Turbo308 · 11-08-2009, 01:46 PM

I did pull the gas cap and it did not seem to help at all... and there was no vacuum wither when the tee was in there and yesterday (There was no noise when I removed the gas cap)...
The only other thing I can think of is removing the filter before the pumps (the silver one) and cleaning it out... but I don't see how it just happens after driving a certain amount of time... and then when fuel pressure builds back up it drives great!...

And I am curious if anyone else out there is driving on these 044's as much as me... I am talking a good long ways (50-75 miles at a time)... and I am wondering if I should hook one up to the hobs switch in the DFI so both are not running all the time??... I was advised against this because it is one more thing to go wrong with the electric system and should not be needed…

huafist · 11-08-2009, 05:40 PM

Are you sure it's not an issue with the regulator?

Turbo308 · 11-08-2009, 06:45 PM

Interesting... how would I check that?... minus buying a new regulator?..

jrtech · 11-08-2009, 10:05 PM

Hua brings up a good point to check the reg!
You have to block the return line, and see if the system builds pressure.

Also did you already try to run just one pump at a time, until failure?

Turbo308 · 11-08-2009, 11:23 PM

I have not run it with one pump until failure... But like I said when it did fail it would not matter if it was one or two it would not build pressure... And the other problem is that when I do here the problem I can almost here the pumps before the fuel pressure drops of... they start to sound like they are struggling to keep pressure..

huafist · 11-09-2009, 08:15 AM

When it happens, plug the return line from the FPR and see if you build pressure.