StrangerWitCandy

So when my 93 Si is low on gas (under half a tank) sometimes the fuel pump wont prime, and therefore the car wont start. This happens after its been driven and then sat for at least a couple minutes (like when i run to the store, when i get back to the car, it wont start) But it always starts after its sat for a day or so.

relevant info would be that it has a b18c motor swap, turbo, runs Uberdata (which I taught myself so i could of done something wrong), and has a used waldbro high pressure fuel pump i got from a friend, again i installed myself and may have fucked something up. And i know its missing on of the like 8 bolts that holds on the top of the gas tank under the rear seat.

So far I’ve thought it may be:
Failing fuel pump
some problem with fuel pressure due to the missing bolt
some problem with uberdata or my ECU
some sort of wiring issue

I’m leaning towards the first two simply because I don’t see how the second two would depend on the amount of gas in the tank. Anyone got any advice?

slowcivic2k

make sure the thermostat ground is connect, its two brown and black wires, that ground to the thermostat housing.

also, check the gas tank for too much vacuum, this happened in my 91 every once and a while, after a run around town, also low on gas. id look into the gas cap idea first, since its the easiest. youd be suprised what a bad gas cap can do lol. post and let us know how it goes.

StrangerWitCandy

how would i check the gas cap? I did notice sometimes if i undo the gas cap (accompanied by a wooshing sound) the car will then start, but most of the time that doesnt work.

slowcivic2k

after a long time of operation like that with vacuum in the tank, it will place additional strain on the fuel pump, and could burn it out, but i never had that problem in my 91 hatch, and it had the stock fuel pump with 250,000 miles, try running around town with the cap loose.

StrangerWitCandy

I was thinking the same thing, that it might of burned up the pump. because its getting worse. And it used to work almost every time to go back, open up the cap, releive the vacuum, then it would start... but lately that works less and less. Maybe its time for a new pump.

StrangerWitCandy

any other input fomr anybody? im trying the gas cap, but its hard to troubleshoot since its such an intermittent problem.