weird fuel pump issue Options

[A TV dinner]

hello everyone. i am trying to install an oem fuel pump on my 72, thats been recently converted back to the djet fuel injection. however, it seems that im not getting any power to the fuel pump now. i have checked the relays and they work, and ive checked the all of the fuses, related or not. when i place an ohmmeter on the two fuel pump leads, with the key on, the meter says that i almost have a dead short, although no wires are physically touching.

any help? this fuel pump is keeping me from 914 pleasure (IMG:style_emoticons/default/blink.gif) (IMG:style_emoticons/default/confused24.gif)

thanks ~alex~

[SirAndy]

i have checked the relays and they work, and ive checked the all of the fuses, related or not.

can you post a pic of your engine bay? and the relay board?

you do have the FI brain hooked up, do you? the fuel pump circuit is controlled by the brain, no brain, no power to the pump ...
(IMG:style_emoticons/default/smile.gif) Andy

[A TV dinner]

i have checked the relays and they work, and ive checked the all of the fuses, related or not.

can you post a pic of your engine bay? and the relay board?

you do have the FI brain hooked up, do you? the fuel pump circuit is controlled by the brain, no brain, no power to the pump ...
(IMG:style_emoticons/default/smile.gif) Andy

yes the computer is hooked up, however i dont know if its working. i was getting power to the pump 2 days ago, and since then i have only removed the fuel pump relay once.

[Cap'n Krusty]

The pump runs only for 1.5 seconds after turning the key to the on position. It also runs once the car starts. An ohm meter can be damaged if you use it on wires with voltage present, IIRC. Wrong test, wrong tool.
You need the center 2 relays on the board. The front socket is for the heated rear glass, the rear one for the heater blower. I suggest you read up on D-jet on Paul Anders excellent site over at rennlist. Someone will be right along to give you the link, I'm sure. The Cap'n

[SirAndy]

i was getting power to the pump 2 days ago, and since then i have only removed the fuel pump relay once.

that might be a clue. the brain rarely dies. but the relays do. and even more commonly, they don't fit snug or the contacts are corroded.

take the relay out and use one of your headlight motor relays for testing (provided the headlights still pop up, in which case the relay is good) ...

make sure the contacts on the socket are clean and also make sure the relay fits tight. you can carefully pry the prongs apart a bit to give it a better fit.

oh, and if you do clean the contacts on the socket with a wirebrush, disconnect the battery first!
(IMG:style_emoticons/default/smile.gif) Andy

[A TV dinner]

thanks everyone. i accidently turned the key once with the ohmmeter on the leads (IMG:style_emoticons/default/blink.gif) . i hope the meter is ok. anyways i have checked the relays to see if there good, however the terminals are probably dirty.

(IMG:http://i51.photobucket.com/albums/f363/ilovedrawingcars/DSC01607.jpg)
(IMG:http://i51.photobucket.com/albums/f363/ilovedrawingcars/DSC01608.jpg)

the engine compartment has been hacked up by the previous owner, but you can see that the relays are there. ill have to clean up the terminals on the relays and board, and see what happens.

thanks ~alex~

[swl]

If you have someone to help perhaps pull the leads off the pump and measure for voltage there. It would help detemine if it is electrical or a stuck pump. Like the good Cap't says - it only turns on for a second so you have to be watching as the key is turned.

[tiim5]

Yesterday, I thought it would be fitting to drive my 914 to the hospital to check on James. Of course it wouldn't start, no fuel pump. I drove the Volvo wagon instead.

Later, I cleaned the relays, after testing them per Andy's tip, checked fuses etc. still nothing.

I recalled the patience James M. exhibited when he installed my Bowlsby harness, it was wonderful to work with him on a project.
I thought, how would he have approched this issue?

I retraced everthing I had done, including removing the air cleaner housing.

Bingo! I discoverd I had pulled off a ground wire from the harness where it attaches to the case below the plenum when I removed the filter unit.

Back in business with pump doing its thing.

Another gift James gave me, be logical and patient.

Perhaps you should recheck all the grounds.

[Dr Evil]

To rule out the relay sockets you can jump the sockets to send power directly to the FP with the key on. This is how the carb guys and folks with other FI systems like me do it.

[A TV dinner]

well.....ok, i finally was able to get to the board and clean up all of the contacts on both the relay board and relays, even the 12 pointers, and i turned the key. all relays work except the fuel pump. so i figure the relay for the pump is bad so i switch it with one that works. turns out its not working (IMG:style_emoticons/default/chair.gif)

SO, i heard from a 914 owner of almost 25 years, and he said that the bottom of his relay board kinda chipped away and corroded. i went ahead and checked mine. some of the tar leading to the fuse for the pump is completely chipped off, and so could this be the problem.

this might make sense because the pump works properly on the bench, however in the car barely worked as of a few days ago. now i have no power at all. mabye its the bottom of the board?????

i hope im not (IMG:style_emoticons/default/dead horse.gif) .........

thanks ~alex~

[SirAndy]

this might make sense ...

yes, unfortunately for you, that does make sense ... the relay board through connections are riveted and not soldered ...

once the tar is gone, the connectors wiggle lose and you get sporadic contact, at best ...

the solutions is to completely strip the tar of the bottom, solder ALL the through connectors, make damm sure they all are OK, then re-apply tar to keep it all safe and in place ...

it can be done and a few members here have. i opted for the "cheap" solution and bought a brand new relay board from porsche as they're still available ...
(IMG:style_emoticons/default/smile.gif) Andy

[A TV dinner]

alright im in for it now.

how would you suggest i remove the tar?? should i simply use a razor blade, or by (IMG:style_emoticons/default/unsure.gif) what ever means possible?

[A TV dinner]

I retraced everthing I had done, including removing the air cleaner housing.

Bingo! I discoverd I had pulled off a ground wire from the harness where it attaches to the case below the plenum when I removed the filter unit.

Back in business with pump doing its thing.

Another gift James gave me, be logical and patient.

Perhaps you should recheck all the grounds.

thanks ill also go out and check the grounds while im at it. never really thought about it.

~alex~

[ziggy101]

before jumpin in to all of this, y not do what i did. my problem was that i replaced the fuel filter, and dripped the pump dry. this caused a bit of air to build up in the pup, and caused it to stay still. i called a mechanic, and he told me to just tap the pump with the key on, and it should free up. i tried it and BINGO! car fired up just like before, and ran great. try this before tearing up the relay board, because they arent too cheap to replace