Won't start
Thread Starter
Racer
Joined: Apr 2002
Posts: 466
Likes: 0
From: Payson AZ
Won't start - MORE
Need a little help. 87 C4 was running, wife shut it off and now it only cranks and won't fire. Plenty of fuel....Gonna have to have it towed or maybe someone here might give a hand. I've asked and some locals think it probably has lost spark. What's the most likely failure? Coil, cap, rotor ? I want to take a couple of parts to where the car is in an attempt to get it started....cheaper than a tow. I have some time till after work today to get some info.....thanks in advance.
Bill
Bill
Last edited by BCinPhx; Apr 2, 2006 at 02:52 PM.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Make some tests to find out what essential component engines need to start and run is missing, namely, spark (and at the right time), fuel and air (and in the correct ratio). Use your timing light while someone cranks the engine to see if you have spark and if it occurs at the right time. Next, put a fuel pressure gauge on the shraeder valve on the end of the fuel rail and turn on the ignition. See if you have normal fuel pressure and then turn the ignition off and observe if the fuel pressure falls rapidly which tells you that you may have leaky injectors. Next, use a noid light (available at parts stores) or a low power 12v lamp and connect it to a removed injector plug to ground and crank the engine. You should see the light pulse which indicates the ECM is pulsing the injectors. Remove the flexible hose from the MAF and try a start, you may have a clogged air filter.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Well, jfb has hit almost everything on the head-accept, you said fuel,
what are you saying ? plenty of fuel in the tank, or are you smelling
plenty of fuel?? if the answer to both is yes-hold the pedal to the metal, and try to start it, a leaky injector(s) make it especially hard to start right after shut down-flooded, holding the pedal down will allow the computer to let it start in flood mode. Hope that helps, and gets you home.
what are you saying ? plenty of fuel in the tank, or are you smelling
plenty of fuel?? if the answer to both is yes-hold the pedal to the metal, and try to start it, a leaky injector(s) make it especially hard to start right after shut down-flooded, holding the pedal down will allow the computer to let it start in flood mode. Hope that helps, and gets you home.
Thread Starter
Racer
Joined: Apr 2002
Posts: 466
Likes: 0
From: Payson AZ
Thanks guys, I towed it home and did some of the things you mentioned. It has intermittent spart and plenty of fuel to the fuel rail. The part that concerns me is that my wife has 2 keys and she tried to start it with the old one and it wouldn't do anything, not even turn over...then she tried the new and known good key and it will turn over but not fire....could the VATS have engaged and if so, how to reset or bypass? I'll be pulling the dist cap and such after work.
Thanks,
Thanks,
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
VATS reads the resistance of the pellet in the ignition key and if it isn't within about 5% it won't allow a crank and it won't tell the ECM to allow the injectors to pulse so that the car cannot be started by pushing it. Your bad key has worn pellet contacts or a defective resistor. Intermittent spark can be from several causes, most likely is a defective spark control module in the distributor or a defective spark coil, or a defective pickup coil.
Thread Starter
Racer
Joined: Apr 2002
Posts: 466
Likes: 0
From: Payson AZ
Well, I've now noticed that there is really no fuel pressure....tried it by myself yesterday and I guess there was some pressure left in the rail....today, with assistance in cranking and by cycling the ignition, there is no fuel out of the shrader valve.....Next thing is, I have never had any reason to check into the fuel pump but now is where I need help....all my manuals are in storage for this car since we just sold our house. Where is the fuel pump anyway? The fuses are all good and I have even taken off the center console to get behind the driver information system and all those fuses are ok. The fuse in the lower right of the fuse box marked FP is just fine but the owners manual indicates this fuse 'feeds' a relay? Where would that be?
Any help or a diagram would help. Where is the fuel pump?
Thanks,
Any help or a diagram would help. Where is the fuel pump?
Thanks,
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
No fuel pressure. Clogged up fuel filter, crimped lines, bad fuel pump. Probably bad pump. The electric pump is located in the tank. Before taking it out test the wiring to see it it gets power. Tan wire was power for my 86. If it lights up then the pump is bad. But first, listen when you turn the key on and you should hear the relay prime the pump. If not the relay is probably bad. The fuel pump is one of the easier things to work on. Remove the gas lid (4) screws. Remove the rubber gas filler neck. The pump flange is held with 9 bolts. Disconnect the feed, return and vapor lines. Remove the bolts and be carful not to mess up the gasket on the tank. Becarful not to drop anything in the tank. Ask me how I know. Get new pump and remove old and install. Install in reverse. If this is the problem. Agent 86 might send you a scan of the diagnostic page. 
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Thread Starter
Racer
Joined: Apr 2002
Posts: 466
Likes: 0
From: Payson AZ
Thanks for the information....if the relay turns out to be bad....where is it located? I am relieved to know where and how the fuel pump is located and how to remove....I've been thru dropping tanks in other vehicles. Thanks, I am at work now and will be checking the board for a while.
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
Originally Posted by BCinPhx
Thanks for the information....if the relay turns out to be bad....where is it located? I am relieved to know where and how the fuel pump is located and how to remove....I've been thru dropping tanks in other vehicles. Thanks, I am at work now and will be checking the board for a while.
Le Mans Master
Joined: Oct 2003
Posts: 6,130
Likes: 2
From: seattle WA
Your relay could be bad-however, even if the relay is shot-when the engine is cranked and oil pressure reaches approximately 4 pounds, it will energize the fuel pump -and if all else is working it will start.First, replace the fuel filter, hook a fuel pressure guage to the schrader valve, turn the key on and watch the FP guage, pressure should build to 41-47 pounds, turn the key off and watch the guage-if it drops quickly-leaky injector(s) if you don't get any pressure-time to replace the fuel pump, and it's a half hour job.
