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captmike13 | Need some help with my 85. | ||
Elite Guru
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For the last few days I've been have intermittent idle and long crank starting issues. Also have had intermittent service engine codes.
I got home and pulled the codes. Here's the list. 24, 34, 42, and 54. Now forgive me for not having my helms but it is in storage still. I'll order another here shortly. I'm staying at my trailer in the campground for the summer so not having a good place to work on it is very very frustrating. Plus paying someone else gets expensive real fast. I really do appreciate the help. I got a list from the other forum that I'll post in a separate thread that has the trouble codes. Once again thanks guys for the help. |
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Posted on: 2011/7/26 23:34
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bogus | Re: Need some help with my 85. | ||
Grand Imperial Pooh-Bah
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Code #24: Vehicle Speed Sensor.
Code #34: Mass Air Flow Sensor Low. Code #42: Electronic Spark Timing. Code #54: Fuel Pump Circuit Low Voltage. If you want my guess... check grounds for corrosion. also, the MAF really kicks off a cavalcade of bugs... I would start there. Check the harness for the VSS, crud there will screw things up. |
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Posted on: 2011/7/27 0:10
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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Jeffvette | Re: Need some help with my 85. | ||
Elite Guru
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24 - VSS
34 - MAF Low 42 - EST 54 - Fuel pump Circuit low voltage I would ignore the VSS code for know and work on the other three. Also ignore the MAF as a low unsteady idle will cause that. I would check fuel pressure and make sure the pump is working correctly. |
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Posted on: 2011/7/27 0:13
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captmike13 | Re: Need some help with my 85. | ||
Elite Guru
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The engine does idle high most of the time when it isn't right somewhere between 1krpm and 2krpms.
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Posted on: 2011/7/27 0:23
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BrianCunningham | Re: Need some help with my 85. | ||
Senior Guru
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intermittent screams harness/connection issues to me.
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Posted on: 2011/7/27 0:28
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_________________
Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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captmike13 | Re: Need some help with my 85. | ||
Elite Guru
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Voltage at the tank is 12V and 10V. Not haveing a book I'm not sure which is the sending unit and which is the fuel pump. Pump does come up to pressure and turn off with the key on but not started.
I don't know if the fuel pump has ever been changed so it would't surprise me if that is finaly going bad. Reason for edit. Added more information. |
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Posted on: 2011/7/27 1:27
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bogus | Re: Need some help with my 85. | ||
Grand Imperial Pooh-Bah
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vacuum leak?
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Posted on: 2011/7/28 5:57
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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captmike13 | Re: Need some help with my 85. | ||
Elite Guru
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I picked up a fuel pressure gauge yesterday on the way home.
I didn't get a chance to do anything due to erands and other after work items that needed to be done. I thought of a vacuum leak too so I'll be going over those too. I'll get some maf and throtle body cleaner too. Ordered another manual also. This is not good timing either. Just got done putting close to 1k in the truck for front end rebuild 96 F250 4wd. We'll get this taken care of with the help of all you good folks. It might take a while but we'll get it done. |
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Posted on: 2011/7/28 10:10
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BillH | Re: Need some help with my 85. | ||
The Stig Moderator
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Mike, I just post this elsewhere. If you get a chance to check the FP before your manual comes in. This is for an LT1 but should be close for your 85.
Checking the fuel pressure is a good way to start (the check valve in the pump may be letting the fuel drain back). FP: Key on - pump should run a few seconds and shut off, 41-47 psi and should hold steady when the pump shuts off. Start the engine, FP should be 3 - 10 psi lower. If you pull the vacuum hose off the regulator, it should return to 41-47. The FP should hold for a few minutes after you shut the engine off. |
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Posted on: 2011/7/28 14:05
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captmike13 | Re: Need some help with my 85. | ||
Elite Guru
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That sounds like a good place to start Bill. I'll update things as I find them out.
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Posted on: 2011/7/28 16:03
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captmike13 | Re: Need some help with my 85. | ||
Elite Guru
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Update. I have a bad FP relay. Checked for key on and no pump on and shut off. Checked voltage at fuel tank and 0V. Traded relay with the overdrive relay (for manual trans.) which happens to be the same one and we had fuel pump on and shut off when pressure came up. So looks like I'll start with replacing the fuel pump relay.
More updates. Off to Napa for parts. I'm gonna replace the fuel pump relay and fuel pump. Being it could be original it is good preventative maintenance. |
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Posted on: 2011/7/28 22:20
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BillH | Re: Need some help with my 85. | ||
The Stig Moderator
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Posted on: 2011/7/28 22:46
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Every man dies but not every man lives. |
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captmike13 | Re: Need some help with my 85. | ||
Elite Guru
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Got the car started. Replace fp relay so far.
key on. Fuel pressure is 39lbs. Key off and it drops like stone. Running fuel pressure is 30lbs and 39 when the vacuum line is disconnected. Car off and again it drops like a stone. Sounds like the check valve in the pump isn't working right. Looks like a weekend project to change fuel pump. |
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Posted on: 2011/7/29 0:50
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BrianCunningham | Re: Need some help with my 85. | ||
Senior Guru
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cool
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Posted on: 2011/7/29 0:52
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_________________
Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
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captmike13 | Re: Need some help with my 85. | ||
Elite Guru
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FSM should be here Friday.
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Posted on: 2011/7/29 1:51
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Matatk | Re: Need some help with my 85. | ||
Webmaster
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Changing pump is an hour job. I've got a write up in the tech section.
Glad you found the problem with the relay! Matthew |
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Posted on: 2011/7/29 2:55
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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captmike13 | Re: Need some help with my 85. | ||
Elite Guru
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Update
Got the fuel pump changed out. Took a little longer than expected due to differences in fuel pumps. The new one needed a wire harness connector and the old one was just spade lugs. See pic. So while the wife was in town getting her nails done I had her pick up wire harness from NAPA on the way home. The car fired right up and no codes. Specs for the fuel pressure are 34-39psi key on no start with a slow drop in pressure. With engine running pressure is lower by 3-10psi. Took it out for a test run and she performed very well. Thanks for the help gurus. |
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Posted on: 2011/7/30 23:56
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