Fb0dy0nly

iTrader: (10)

Hey guys I dunno if this is the right sub-forum for this question but I figured it was the best choice since it has to do with my fuel pump electronics. I usually can find info I need by searching around and doing countless google searches on different sites but I havent found anything specific to my issue so I thought I would ask you guys, the pros, for any suggestions/help.

First off I started having issues with the car being sluggish when I would stomp on the gas and get the rpms up there, I just figured the car needed a tune after all the work Ive done to the engine, exhaust, etc but then it started to randomly die on me and I would have to sit and keep cranking it and finally it would fire back up and run again or having to give it a little gas upon cranking to get it started. This turned into it completely not running at all and just constant cranking or it would fire up and then die right away after starting, even with tapping the gas petal... So I figured it was a fuel issue. I tested this by using starting fluid in the intake and it started right up and then died but I knew it was fuel as I couldnt hear the pump priming at all either. Tried the easy stuff like moving around relays and fuses and it still was dead so I figured it was the pump. Went ahead and changed the pump to a super low mileage delco OEM unit I got from a yard. After changing it, I tried starting it and it did the same thing again, start up and then die right away. Tried a different relay from the ac comp and bam it came to life and ran great. Took it out for a spin and it was great, ran wonderful. Problem solved right? Hah I wish.... so the next day I take it out and drive about 20 miles, mostly highway, and it ran great the whole time, no stumbling, rough idle or wired noises. Upon trying to start it to get back home, the SAME thing happened again; cranks over and then dies right away. Towed it home and inspected it really good and tried yet another relay, this time the fog lamp one as they are all the same part # relay. Again it starts back up and runs great. Next day I go out to drive it to work and it happens again, cranks over and starts and then dies out right away again. At this point Im getting frustrated as hell bcuz I have no idea what the issue is. I checked ohms at the relay box and seems to be getting the right amount of current. Checked all the wires running to and from the relay/fuse box and everything seems ok, no loose or burnt/broken wires looking out of place. Same thing with the other end at the tank, everything looks ok physically. What is even more weird is that when I try these relays that keep going out in the fuel pump spot they all work in the other spots though. I can swap out the working horn relay with the bad fuel pump one and the horn works fine but the relay doesnt work in the fuel pump spot.

I could see it being a bad relay but when I try the bad one in another spot that isnt the fuel pump it works fine and when I try a new relay in the fuel pump spot it works fine for basically one drive, once I shut it off, it goes bad and doesnt work in that spot anymore but works in all other relay spots that uses the same relay.

What could be causing the relay to stop working after just a few starts? Like I said I played with the wires over there and that did nothing from keeping it from starting or not but at this point I have to basically put a new relay in it every time I drive it but its not like its blowing the relay and killing it because they work fine afterwards in other spots, something is keeping it from working there though. Its very confusing I understand and I am not good with electrical issues like this. My next idea was to get under the car and check out the wiring running to/from the tank and pump but from afar, it seems alright. Does anyone have any other suggestions as to why this relay issue would be happening like this? Why does a new relay work for a little bit and the car run perfectly fine and then stop but still work in other spots like the fog lights or horn like the relay is not bad? I could understand if none of the relays worked at all, then I could see a bad ground or wire issue or if the relay stopped working and didnt work in any of the spots (fuel pump, fog lights, horn etc) then I would say its a bad relay but what would cause it to work fine and then not and then ok again in another relay spot? Any and all help is appreciated, thanks guys!

76larkman

well you have 4 wires to relay? one #30 goes to positive battery so should be hot all time. #87 goes to pump, next is #86 & #85 one is trigger with key out of pcm other is ground. check with test light see if you lose power on either power wire. And check for losing power at pump.

Fb0dy0nly

iTrader: (10)

Thanks for the reply, I checked to make sure the relay is getting the right amount of power and its not spiking or fluctuating any which is good. How do I check to see if the wires are losing power? Do I test while trying to start the car or just when the key is turned to on? I think the pump is getting power fine because I checked the wires there on top of the pump and each are getting the 5 volts its says its suppose to have but I only checked with the key on and not while cranking/starting.

Someone I talked to suggested that the block could be the problem that the relay sits in as it draws a lot of current and the relay could be coming loose or breaking contact somehow when it heats up because the problem only happens after driving the car for a bit and then shutting it off and trying to start it again. For everything to work fine otherwise seems to suggest something weird is happening at the relay block causing it to lose contact or send signal to the pump.

I also am having a buddy bring me over a jumper with a fuse to see if the pump comes on with that so I can make sure the PCM/BCM are doing their job.

Does anyone know where the fuel pump relay is grounded at? I just want to make sure I am getting a good ground as well bcuz I know how fidgety those can be on a car. Ill try and find a schematic in the meantime...
Thanks

notnilc20

Did you ever figure this out? Sometimes my car does similar things. After i drive it for a while and turn it off and then go to restart it, it cranks extra long and finally starts with a rough idle.