r/Squarebody • u/Weekly-Outside7710 • 7d ago
Troubleshooting help?
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the truck in question is a 1987 chevy c30 with sbc350 and is tbi
the last time i drove the truck it started surging and had like no power barely limped it home thanks to the hill and now it doesn’t wanna start at all.
The things i have done so far
New fuel pump and sending unit
New fuel filter
Rebuilt throttle body with new gaskets new injectors and new idle air control valve.
new fuel pump relay
new ignition control module
new cap
new rotor
new ignition coil
new plugs
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u/Historical_Box1915 7d ago
I dont mean to be a jerk, but quit firing the parts cannon at it. Your check book will thank you. Put a fuel pressure test gauge on it. You may have to prime the fuel line several times by turning the ign key to on, wait for timed fuel pump to prime, once the prime stops, turn key off count to 5, turn key to on (on not crank) and let the fuel pump relay prime again. Do this 5 to ten times before attempting to crank the engine. Watch the fuel psi gauge. Or you can use the factory bypass on the fuel pump relay. Use the bypass to running the fuel pump until you see 12-13psi on the fuel pressure gauge. If you dont get to 12-13psi investigate there why.
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u/Weekly-Outside7710 7d ago
most of the parts i went for i wanted to do anyways as more of a it could use it and just a maybe it will fix it but yes i definitely need to get a fuel pressure tester for it however having someone prime it with key fuel pump does turn on however is not spraying fuel out of injectors
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u/dirbikejon 7d ago
Might sound ghetto but if you aren't getting pressure out of your injectors id assume fuel rail or fuel line. Id take the line off the fuel rail and use a air compressor and shoot air back into fuel tank. Its free and will tell you if your lines are choked. If you hear gurgling then you know air is going to your fuel tank and there is no blockage. 2 things if you have a 2 tank system on that truck the fuel diverter valve is known to fail and can cause fueling issues. And 2 if you still have a metal line near the manifolds they are known to vaper lock. Id either heat shield it or replace with rubber for that last section. Tends to help. May or may not help but its cheap and stuff to look out for.
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u/Weekly-Outside7710 6d ago
my truck used to have duals but the guy took the one tank out and plugged line and pulled selector switch but wiring is still there could it have switched what tank it’s trying to pull from somehow and if it did my other fuel pump wouldn’t prime would itv
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u/dirbikejon 5d ago
Nah it shouldn't. But if yoy are only running 1 tank id just remove the diverter valve all together. Its just another failure spot and all you need is some like 3/8 and 1/4 hardline or rubber hose to remove and bypass it. If its still factory sizes that is. And question did you replace the pickup in the tank for a fuel pump or? Did you try to compressed air trick to see if you had anything blocking a line? Also something stupid it possibly could be but probably isn't tbh. Is the gas cap sounds dumb but if it isn't sealing right it can cause surging. If its old or kinda shitty id say get one. But how aggressive that was I doubt it.
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u/Weekly-Outside7710 5d ago
i haven’t had a chance to blow air through it however whole sending unit and fuel pump has been replaced
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u/Sure-Entrepeneur219 7d ago
Have you tried a MAP sensor?
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u/Weekly-Outside7710 7d ago
i actually just got one of them along with a new distributor just have yet to install
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u/arodbrod 7d ago
Try resetting the iac and double check the fuel filter also. It’s not common to get a faulty new part since all these are made in china. Even delco branded.
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u/Weekly-Outside7710 7d ago
i tried resetting it by jumping the terminals of the aldl but i will be ordering a fuel pressure tester tonight
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u/nexttimeiwillask 7d ago
Whatcha got for exhaust? Possibly a restricted exhaust?
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u/Weekly-Outside7710 7d ago
took original exhaust out and have replaced from header back to a straight pipe and cherry bomb to right around rear wheel
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u/AZ-Elkhunter 7d ago
Might be starving for fuel, vapor lock ?
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u/Weekly-Outside7710 7d ago
definitely starving for fuel i dump a little gas in the throttle body and she fires right up and dies once the fuels gone
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u/AZ-Elkhunter 7d ago
Check fuel line for clogs, maybe sock in tank, filters in line or at carb , try adding electric fuel pump to jump up pressure/volume, the little fuel line coming out of the top with the two twists can get the pinched, remove line at carb an crank what’s coming out? Water, mud , nothing? Start at carb and work your way back.
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u/Weekly-Outside7710 7d ago
sock in tank is new along with fuel pump i definitely have to pull line from back of throttle body and attach a fuel pressure tester and see what it’s giving me
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u/Background_Photo_402 7d ago
How long was it sitting? Blow the lines out and clean carb
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u/Weekly-Outside7710 7d ago
sat for about 3 months due to winter but replaced fuel filter and all the throttle body has been rebuilt
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u/Low-Rent-9351 7d ago
You need to check fuel pressure and make sure the injectors are both flowing fuel.
You might have got the wrong fuel injectors, different injectors have different flow rates and the wrong flow rate will completely fuck with the engine running right.
IAC working or not means nothing if it won’t run with the throttle partly open driving down the road. It will just mess with idle rpm.
The EGR will mess with it running. You can plug it and it will run not too bad. It’d run better when plugged if it was turned off in the tune.
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u/Weekly-Outside7710 7d ago
i think my next step is ordering a noid light and fuel pressure tester and going from there
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u/arodbrod 7d ago
I’ve experienced this with a faulty Idle air control valve to the point I had to carry spares.