91 no start
Thread Starter
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
91 no start
I just had a new fuel pump put in a few weeks ago and Im right back to the car wont start o run, it sounds as if it fires for about one rpm and if I hold the key it just turns. One day it just started and ran again the next no go.
The service manual I have on CD might be ok if I could just traverse it well I think.
Specifically, Im curious about the wiring to the fuel pump relays (so if I get there I know what to check) and fuses, and the ALDL pin G. I thought I could watch it fr voltage with the key on to see if its priming, but I get 12 all the time there and drops to zero when turning key to try and start.
Can someone help me find the appropriate section in my so called service manual or help me with a couple quick tests to do with my dvm, before Im prepared to go through the entire diagnostics from step 1?
The service manual I have on CD might be ok if I could just traverse it well I think.
Specifically, Im curious about the wiring to the fuel pump relays (so if I get there I know what to check) and fuses, and the ALDL pin G. I thought I could watch it fr voltage with the key on to see if its priming, but I get 12 all the time there and drops to zero when turning key to try and start.
Can someone help me find the appropriate section in my so called service manual or help me with a couple quick tests to do with my dvm, before Im prepared to go through the entire diagnostics from step 1?
Thread Starter
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
Thank you I found that and Im starting to learn my way around the pdf a little bit now. I dont have a fuel pressure guage still and when I called AZ about their rent a tool one they said $150 for the deposit. I actually cant hear the fuel pump prime but the power ant sound lasts just long enough that I cant be sure, nso I need to pll the fuse for the radio I guess and probably the cooling fan since its coming on when the key is on. oo much noise to listen for the prime and be sure thats why I wanted to look for 12 volts at pin g on the aldl but it shows steady 12 and then goes to zero so Im thinking that 12v is through the fp coil, and grounding pin g would make it run, but not sure enough of the circuit to try it yet.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
Fuel pressure gauge would indicate if fuel pump is turning on and if pressure is adequate for engine to start. Fuel pressure gauge many times can be rented from parts stores, who have tool loaner program.
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
A plus to the 'digital' FSM, very dependent on whose you have but if you use the proper terminology the search function can work very well for you. Use the 'drop-down' in the EDIT button to FIND. Again dependent upon whose FSM there's likely an index available in a 'left column' that eases maneuverability considerably. The ELECTRICAL DIAGNOSIS section should be an easy find in the 'left index pane' - Multi-Port Fuel Injection VIN 8. What type of a device are you trying to view it on?
NO START is a good search term - the advanced search gets you hits for the entire FSM.
NO START is a good search term - the advanced search gets you hits for the entire FSM.
Last edited by WVZR-1; Nov 1, 2018 at 07:47 AM.
Team Owner
Joined: Jul 2004
Posts: 28,472
Likes: 3,290
From: Hartford WI
Thank you I found that and Im starting to learn my way around the pdf a little bit now. I dont have a fuel pressure guage still and when I called AZ about their rent a tool one they said $150 for the deposit. I actually cant hear the fuel pump prime but the power ant sound lasts just long enough that I cant be sure, nso I need to pll the fuse for the radio I guess and probably the cooling fan since its coming on when the key is on. oo much noise to listen for the prime and be sure thats why I wanted to look for 12 volts at pin g on the aldl but it shows steady 12 and then goes to zero so Im thinking that 12v is through the fp coil, and grounding pin g would make it run, but not sure enough of the circuit to try it yet.
Thread Starter
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
Thank you everyone, I just finished the testing. I did remove the fuse for the radio so the power ant wasnt making sound. No prime was the result, o I looked over the diagram finally (maneuverability is what I needed, where the heck ckt 120 is they didnt say? Anyway I fed 12v to pin g no hum so Im thinking a flaky wiring somewhere or the new pump only ran a few weeks. Expected decent quality from a company that made carbs for 3o years or whatever.
Probably just get the Delphi locally this time I can only get a refund towards the same brand at RA. I dont want another of theirs.
BTW I did find 120 just dont know how things are referenced yet.
Probably just get the Delphi locally this time I can only get a refund towards the same brand at RA. I dont want another of theirs.
BTW I did find 120 just dont know how things are referenced yet.
Last edited by ToniJ1960; Nov 6, 2018 at 07:23 PM.
Team Owner
Joined: Jul 2004
Posts: 28,472
Likes: 3,290
From: Hartford WI
Thank you everyone, I just finished the testing. I did remove the fuse for the radio so the power ant wasnt making sound. No prime was the result, o I looked over the diagram finally (maneuverability is what I needed, where the heck ckt 120 is they didnt say? Anyway I fed 12v to pin g no hum so Im thinking a flaky wiring somewhere or the new pump only ran a few weeks. Expected decent quality from a company that made carbs for 3o years or whatever.
Probably just get the Delphi locally this time I can only get a refund towards the same brand at RA. I dont want another of theirs.
BTW I did find 120 just dont know how things are referenced yet.
Probably just get the Delphi locally this time I can only get a refund towards the same brand at RA. I dont want another of theirs.
BTW I did find 120 just dont know how things are referenced yet.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
It isn't always easy to hear which is why you should use a gauge. Even if you do hear it, you can't tell if it gets the right amount of pressure with your ear or whether it holds pressure. Before I go condemning the pump and replacing it, have you checked if you get power at the pump? If there is a break somewhere, you have a different issue. Also maybe try applying power at the pump and check the pressure spike. I'm not sure why you like to use the hearing thing to check and then use it to determine what parts to throw at it.
So I guess ill go back to the book tonight and tomorrow or the next day if it doesnt snow etc to give them $150 for their deposit to use teir fuel pressure tester.
It does start to run just for a sec and if I touch the gas pedal it will keep running, but it wants to be all or nothing with a small effort. It made me think back to a few days ago the last time I got it to run it had some weird wicked aceleration about a block or two before I got home and parked it.
I checked for codes and it flashed 12 over and over via the check engine light but the heater control lcd screen is just a nice depressing warm glow .........
Team Owner
Joined: Jul 2004
Posts: 28,472
Likes: 3,290
From: Hartford WI
IDK if it is not holding pressure but seems like a pump failure so far if the power is going past the tank to the pump. The gauge will be able to tell if it holds pressure ,assuming it gets pressure.
Thread Starter
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
oh oh blank lcd fuse still out sorry
Last edited by ToniJ1960; Nov 8, 2018 at 06:05 PM.
Team Owner
Joined: Jul 2004
Posts: 28,472
Likes: 3,290
From: Hartford WI
Crimp off the return line to see if it will hold pressure. Here is how it should go. If it could run like you said, it should have some pressure. If it spikes up on prime and falls quickly, crimp the return line to see if it will hold pressure. If it does, your issue lies between the pump and the regulator. If it holds pressure but bad pressure, you have another issue to chase.
Last edited by aklim; Nov 9, 2018 at 12:05 AM.
2nd Gear
Joined: Nov 2018
Posts: 2
Likes: 0
Hello new to forum and Corvettes.. My Wifes 91 ran fine when parked then will not start. No voltage at Batt terminal on HEI cap. No spark have tach disconnected from cap also.
Chilton tells me I I have 7volts there start checking the pic up coil. Have you guys seen this with no volts at that terminal? Thanks in advance or any help.
Todd
Chilton tells me I I have 7volts there start checking the pic up coil. Have you guys seen this with no volts at that terminal? Thanks in advance or any help.
Todd
Last edited by toddmc24; Nov 11, 2018 at 11:07 AM.
2nd Gear
Joined: Nov 2018
Posts: 2
Likes: 0
Hello new to forum and Corvettes.. My Wifes 91 ran fine when parked then will not start. No voltage at Batt terminal on HEI cap. No spark have tach disconnected from cap also.
Chilton tells me I I have 7volts there start checking the pic up coil. Have you guys seen this with no volts at that terminal? Thanks in advance or any help.
Todd
Chilton tells me I I have 7volts there start checking the pic up coil. Have you guys seen this with no volts at that terminal? Thanks in advance or any help.
Todd
Thread Starter
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
ok so I have a fuel pressure tester and was all set to do the test, and I finally spotted the valve or the cap at least. I took off the cap and surprise it smells like gas inside of it I could see it was a little wet too.
Could it be losing pressure through there I doubt that plastic cap is supposed to hold that kind of pressure? I decided Im not smart enough to know yet wether its safe or a good idea or necessary to continue but Im smart enough to find out first.
Could it be losing pressure through there I doubt that plastic cap is supposed to hold that kind of pressure? I decided Im not smart enough to know yet wether its safe or a good idea or necessary to continue but Im smart enough to find out first.
Thread Starter
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
The fuel test showed 30 psi key on and it held at that for a few minutes with no drop. So I suppose pinching off the fuel return line is next and where do I find it I do see one fuel connection at the top of the fuel rail area on the drivers side but I cant see another one anywhere.
I did take the small hose or tube off the fuel pressure regulator and smelled a slight fuel smell in it.. I also have ordered a scanner that supposedly will show live data on obd1. Sure it will come in handy later on sometime at least.
I did take the small hose or tube off the fuel pressure regulator and smelled a slight fuel smell in it.. I also have ordered a scanner that supposedly will show live data on obd1. Sure it will come in handy later on sometime at least.
Thread Starter
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
Im guessing the problem is pressure regulator or the pump. I found a picture showing the return line connection at the regulator coming out on the passenger side? Or do I have them backwards. And where is the easiest place to try to pinch off the return? The gauge showed it holding at 30 and when I released the pressure not even a drop made it out of the hose on the tester.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
30 psi is too low it should be 44+. Fuel filter? If you remove "well" around fuel filler you will have access to fuel supply and return hoses. Pump is mounted to sender. Fuel filler is part of sender. Supply hose is 3/8 return is 5/16.
Thread Starter
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
It seems weird its so intermittent run one day wont the next then will then wont for anythng.