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91 no start

Old 10-30-2018, 06:42 PM
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ToniJ1960
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Default 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?
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Old 10-30-2018, 08:55 PM
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Look in 6E then look for chart for " no start"
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Old 11-01-2018, 05:46 AM
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Originally Posted by Kevova View Post
Look in 6E then look for chart for " no start"
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.

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Old 11-01-2018, 08:00 AM
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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.
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Old 11-01-2018, 08:42 AM
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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.

Last edited by WVZR-1; 11-01-2018 at 08:47 AM.
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Old 11-04-2018, 09:51 PM
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Originally Posted by ToniJ1960 View Post
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.
2 things. 1 turn the power ant off by turning the radio off so you can hear, if that is what you are trying to use. 2. Don't bother to hear when you can verify. Borrow the tool, turn it on and remove all doubt as to whether it is priming or not. You get one shot at this and then you wait for a while (a few minutes) till it allows a re-prime. So if is priming, we know it works since we have seen the pressure spike. If it doesn't hold pressure, we can investigate further.
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Old 11-06-2018, 08:21 PM
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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.

Last edited by ToniJ1960; 11-06-2018 at 08:23 PM.
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Old 11-06-2018, 08:58 PM
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Originally Posted by ToniJ1960 View Post
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.
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.
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Old 11-08-2018, 06:32 PM
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Originally Posted by aklim View Post
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.
Youre right I never got to take it out I saw the connector and checked there and found the 12v for a few seconds prime voltage for the fuel pump, and a very low resistance across two terminals on the pump side and stopped myself from going any further I cleaned the connector put it back together and the pump noise was definitely obvious.

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 .........
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Old 11-08-2018, 06:36 PM
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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.
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Old 11-08-2018, 07:02 PM
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Originally Posted by aklim View Post
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.
It ran for as long as I held the pedal down \just a tiny bit, maybe 5 or 6 seconds and no fuel smell in the hose on the throttle body I puled off but it could be losing pressure so off to ``borrow` the tester soon.


oh oh blank lcd fuse still out sorry

Last edited by ToniJ1960; 11-08-2018 at 07:05 PM.
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Old 11-08-2018, 09:52 PM
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Originally Posted by ToniJ1960 View Post
It ran for as long as I held the pedal down \just a tiny bit, maybe 5 or 6 seconds and no fuel smell in the hose on the throttle body I puled off but it could be losing pressure so off to ``borrow` the tester soon.


oh oh blank lcd fuse still out sorry
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; 11-09-2018 at 01:05 AM.
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Old 11-11-2018, 12:04 PM
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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

Last edited by toddmc24; 11-11-2018 at 12:07 PM.
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Old 11-11-2018, 12:39 PM
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Originally Posted by toddmc24 View Post
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
According to Chilton's this is fed from Ignition switch does anybody now If there is a security on the ign switch that keeps it from suppling power to dist?
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Old 11-17-2018, 07:12 PM
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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.
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