Fuel issue. could it be my pump?

I was taking my car for a ride today and all of a sudden it died. Went to restart it and it would start for a few seconds but run with very low RPM’s and then die again. I was able to get a tow to my house and looked for a vacuum leak as that was my 1st thought, didn’t see anything with vacuum so went on to fuel, and that seems to be my issue.

I checked the fuse’s relating to the fuel pump under the hood and driver side floor board and they were good. I used the black wire behind the battery and ran a wire to the battery to test the fuel pump and it seemed to run, and after i did that and would try and start the car it would fire like normal but then quickly die again, leading me to believe it not getting fuel as well as dry plugs. could it still be the pump? i tend to think not, but what else should i check that would stop the pump from kicking in. I looked for some relays to test but i’m not sure where they are located. Ive spent the better part of the day trying to DX my issue, but still on the newer side to the platform and have lots to learn. Any help or ideas would be greatly appreciated.

Car is a 1995 VR4 spyder.
Has a Chrome ECU.
denso supra fuel pump

The pump only runs when the car is cranking, unless you have it set up differently in Chrome. I’m betting you blew a coupler, ie have a massive boost leak.

The low RPM and dying as a classic indicator of that.

I will look again, but i checked everything a couple of times. but yes that was my 1st thought as well. I wasn’t even close to being under boost when it happened was cruising about 27mph in 3rd. The part i don’t get is when i test the pump using the test port by the battery and it kicks on. When i go to start the car right after that it will fire up for second as it burns off that gas. Then won’t start again.

i should have stated that unless i run the pump using the test port, it will not fire and idle low anymore. it will just turn over and not start. weirdly enough it stopped the quick start and low idle after i got the car home. i disconnected the battery for 10 minutes just incase the ecu needed to be reset or anything (was grasping at straws) since i did that i will not fire… just turn over… again unless i manually run the pump from the test port then it will fire for a second and then die again.

I’ve checked a couple more things off the list. The relay under the air cleaner checked out, the MFI relay by the passenger side floorboard appears to be good. I ordered a fuel pressure test gauge and its on its way.

back up and running. I missed a relay, I have a hotwired pump and had a wire from my fuel pump harness to my relay get hot and melt. I’m not sure why it didn’t pop a fuse first. But i got everything replaced and put a direct fuse to it now incase it ever happens again. I’m just thinking a wire got lose from the connection and got hot. Checked currents after the repair and everything was working great.

I can’t help to to hear Joe in my head saying this is why we don’t modify these cars :smiley: but it was something the original owner did. I’m just happy i didn’t shotgun a pump at it and took my time to diagnose the problem and in 3 days i’m back up and running!

On a positive note. I now am very familiar with our whole MFI system. so it feels good to have a better understanding of my car.

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Glad you got it solved. If I remember right there were issues with some of the hotwire methods for the fuel pump in the past that was fixed with better methods. It appears the previous owner never corrected it before the car landed in your hands.

I’d look up some of the kits/methods and redo the entire hotwire set up.

And yes, isn’t it amazing how chasing down a problem can teach you solutions to problems you don’t actually have, but you have that knowledge in the back of your head. I once spent 8 hours searching online for a solution to a problem with a Stealth I was working on. I learned so many things along the way that had nothing to do with the issue I was having, and those things stayed in my brain. I finally hit that AHA at the 8 hour mark and found the right post that pointed me to a solution.

Even though it was 8 monotonous hours of searching it was invaluable for my knowledge base I gained.

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I have done my car fitted realy at the fule pump end of the car with fused cable from battery