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Discussion Starter #1
Fuel Pump no start

First time post, 23 year Corvette owner/daily driver. Second LT-1, '94 6 speed Polo Green 68k miles. See if this makes sense. Car died on the way to work Friday, cranked but would not start. Got it home and attached fuel pressure gauge held steady 40+ psi, pulled the codes via paper clip, and only got a front right O2 sensor (64?), had O2 problem with my first LT1 auto, so got all three and changed them Saturday, car started and ran although it had rough idle. Got in it Sunday AM and again it cranked, but no start. Put the guage back on, and zero fuel pressure. Checked at connection above fuel tank to pump, and was pullin 12.32 volts off middle wire. Appears to be an intermittent issue with pump, and replacement should correct problem. Changed one on my'85, so I'm familiar with the job. This sound reasonable, or could it be something else, the fact it's showing twleve volts at pump lead me to believe the relay is good and pump is bad. Thanks!
 

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Just remember that voltage doesnt do the work, amperage does, just because the circuit(wires, relay, fuses) can transfer 12.32 volts doesnt mean they can carry the at least 5 amps required to run the pump. Heres the real test.


Make a high cuurent test light out of a sealed beam(or whatever youve got) style headlamp, attach one lead from the lamp to pumps ground supply and the other to the pumps voltage supply(just like the voltmeter)

If the bulb lights at full brilliance then you know the circuits are good enough to run the pump, and youve got either a bad pump or bad pump controls.
 

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Discussion Starter #3
Thanks for reply, however I changed pump, and now again have 40+ psi at the guage, when I first cranked it sounded great for couple of minutes, revved nicely and all, about the time I got out to check for leaks at the tank it died. Still have excellent pressure at the rail, and it tries to start, but won't. Checked vacum hoses, electrical connections, etc...
 

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Discussion Starter #4
Here's my issue, car died on the way to work Friday, towed it home and attached fuel pressure gauge, it held a steady 40+ psi, paperclipped the codes, and got a front right O2 sensor (64?), had O2 problem with my first LT1, so replaced all three, car started and ran although it had rough idle, next day it turned over but wouldn't start. Put the guage back on, had zero fuel pressure, replaced pump last night, car started and ran great for about two minutes, and then stumbled and died, still have 40+psi at fuel rail, car tries to start but won't. Maven suggested in earlier post a possible amp problem, I did have a lot of battery crud around the battery and one of the maxi fuses block, cleaned it well, systems off that fuse block seem fine, is there a relay in that vacinity that could be affected by the battery sludge? Put a guage per FSM and checked spark at a couple of plugs and both showed fire. Hope it's not my opti spark, I'd just replaced all that on my other 94 before selling it. This one has 68k miles and is setting no codes. I've been working on my own Corvettes over 20 years, nice to receive help from others that have been there, and look forward to returning the favor.
 

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Discussion Starter #5
After going through everything else, went back to basics, fire, fuel and air, took air induction hose off and spayed a small quantity of starter fluid in, and car started and ran for a couple of seconds, it's not optispark, or fuel pump it must be something not allowing injectors to function properly, any ideas?
 

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Discussion Starter #6 (Edited)
Follow up

Got it started, but idles rough, and exhausts smells strong, like bad gas, but called Chevron, and they claim no one has reported any problems. It's similar to bad O2 sensor, but I've replaced all three and have no MIL. Unplugged MAF and TPS to verify MIL functions, and it did. Now I'm wondering about optispark again. Sorry, car is 94 lt1 6 speed all stock.
 

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So youve got a no start now, with good fuel pressure(whats the gauge read?) and spark on more than one plug??

Do you have a noid light you can check for injector control with??
If so check it out if not you can make do with out it.

Check the injector fuses, see if theres power at the fuse with the key in "RUN".

Check to see if theres power at the pink wires in the injector connectors with key in "RUN"(you can use the same headlight testlight trick).

Connect your test light(NOT the headlight one) to BATTERY POSITIVE and touch the probe to the injector control wires(the NOT pink wires :)) and crank the engine the test light should flash/flicker.
 

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So youve got a no start now, with good fuel pressure(whats the gauge read?) and spark on more than one plug??

Do you have a noid light you can check for injector control with??
If so check it out if not you can make do with out it.

Check the injector fuses, see if theres power at the fuse with the key in "RUN".

Check to see if theres power at the pink wires in the injector connectors with key in "RUN"(you can use the same headlight testlight trick).

Connect your test light(NOT the headlight one) to BATTERY POSITIVE and touch the probe to the injector control wires(the NOT pink wires :)) and crank the engine the test light should flash/flicker.
I was just going to say all that.









:laughing:
Kidding.
 

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Good to know youve got my back Patrick.:D
 

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Pop your gas cap, if it doesnt smell like gas its not. I have had a couple bad tanks of gas before. The station may not admit to it either. Its just not in there best interst.
hope this helps
 

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Okay, another thread :D

Did you try what I suggested here?

I see youve also complained about fuel pressure that wont hold with key off, this is usually related to leaking injectors or failing fuel pressure regualtors, both of these conditions will also lead to the hard starting, strong exhaust, and rough idle you're experiencing.

To check for a bad FPR, block off the return line and check to see if the pressure still drops, if it does its injectors leaking/stuck on or the check valve in the fuel pump module.

When it leaks down with the return line blocked off pull the plugs and see if they are wet to verify if its an injector or check valve issue.


Check all your vacuum hoses and fittings. Try to run the car with the MAF unplugged, see how it runs. if no change, plug it back in and then disconnect the MAP, see how it runs with MAP disconnected. If it runs noticeably better with either of these sensors unplugged then that sensor or its circuits are broken.






Merged 3 related threads.
 

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somethings wrong here, seems this problem is cropping up all over the place. my 87 is doing the same things. i got code 22, 44 high voltage to MAF low voltage to TPS. adjusted TPS to .54 same deal. just cant figure it out :thud: :thud:
 
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