fuel or spark problem
Thread Starter
Racer
Joined: Jun 2004
Posts: 252
Likes: 0
From: Brevard NC
fuel or spark problem
1991. My dad passed away a year ago and I had been storing it. My gas tank got water in it and the car wouldnt start. We cleared the tank and replaced the fuel filter and it was running great for about 10 minutes and just died. We were still getting clean fuel so we checked spark. We installed a new distributor and are now getting good spark. Two of my cylinders are not getting fuel now. The car will not crank. I was wondering if there was a module or some type of control that works like the distributor to control the fuel injectors. It would seem odd that two injectors just went out. No trash was in the filter either. NEED HELP!
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
All 8 injectors are connected together. If the others are working then the injector, connector, connection or wires are bad.
The fuel injectors are controlled by the ECM = Engine Control Module (some say Electronic Control Module).
Your symptoms and description don't match. "The car will not crank" means that NOTHING happens when you turn the key to the START position. Yet you say two injectors aren't working. How would you know that if the engine doesn't crank or run?
If the engine doesn't crank you should still hear the starter relay clicking (inside the dash). If that's not happening then you probably have a problem with VATS. See here:
http://www.joestradingpost.com/vats/
Maybe you meant the engine does not run? The ECM needs DRPs = Distributor Reference Pulses to synchronize the fuel injectors. If the DRPs are not there then the engine won't run. There's a 4-pin connector on the distributor that connects the distributor to the ECM. Is that plugged in? Hopefully your new distributor is compatible with the ECM...
The fuel injectors are controlled by the ECM = Engine Control Module (some say Electronic Control Module).
Your symptoms and description don't match. "The car will not crank" means that NOTHING happens when you turn the key to the START position. Yet you say two injectors aren't working. How would you know that if the engine doesn't crank or run?
If the engine doesn't crank you should still hear the starter relay clicking (inside the dash). If that's not happening then you probably have a problem with VATS. See here:
http://www.joestradingpost.com/vats/
Maybe you meant the engine does not run? The ECM needs DRPs = Distributor Reference Pulses to synchronize the fuel injectors. If the DRPs are not there then the engine won't run. There's a 4-pin connector on the distributor that connects the distributor to the ECM. Is that plugged in? Hopefully your new distributor is compatible with the ECM...
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
1991. My dad passed away a year ago and I had been storing it. My gas tank got water in it and the car wouldnt start. We cleared the tank and replaced the fuel filter and it was running great for about 10 minutes and just died. We were still getting clean fuel so we checked spark. We installed a new distributor and are now getting good spark. Two of my cylinders are not getting fuel now. The car will not crank. I was wondering if there was a module or some type of control that works like the distributor to control the fuel injectors. It would seem odd that two injectors just went out. No trash was in the filter either. NEED HELP!
how did you deduce that 2 cylinders are not getting fuel? it should "crank" if the key/starter circuit is working. it should start and run with 2 injectors not firing, or even one bank not firing.
check the 2 injector fuses.
were you getting ANY spark when you checked? did you replace cap, coil, etc? did you install new distributor so that it is in correct timing, etc, etc.?
my guess is that anyone unfamilar with the l98 as you are would not know how to do that.
too much missing info and conflicting info to focus on a solution.
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
Yep...
post some clear cut symptoms and you WILL get clear precise solutions..
be clear...does the starter turn the engine over?
does it burp fire or attempt to start?
what is the fuel pressure from the test gauge?
how do you KNOW the inj are actually operating? noid lite? gauge observation during cranking?
Do you understand how this system works? VATS permission to the starter AND fuel inj circuit? then the dist MUST signal ok to the fuel pump relay OR fall back on oil pressure back-up? Get all that? 2 second fuel pump prime at Key-ON.. 40 psi min fuel pressure to start-up.
Sounds to me like you desparately need a FSM and someone with some C4 experience.
..and some C4 test tools.
post some clear cut symptoms and you WILL get clear precise solutions..
be clear...does the starter turn the engine over?
does it burp fire or attempt to start?
what is the fuel pressure from the test gauge?
how do you KNOW the inj are actually operating? noid lite? gauge observation during cranking?
Do you understand how this system works? VATS permission to the starter AND fuel inj circuit? then the dist MUST signal ok to the fuel pump relay OR fall back on oil pressure back-up? Get all that? 2 second fuel pump prime at Key-ON.. 40 psi min fuel pressure to start-up.
Sounds to me like you desparately need a FSM and someone with some C4 experience.
..and some C4 test tools.
Last edited by leesvet; Sep 22, 2012 at 08:36 AM.
Thread Starter
Racer
Joined: Jun 2004
Posts: 252
Likes: 0
From: Brevard NC
sorry for the lack of clarification. You are correct, it turns over but will not run. The garage I took it to replaced the distributor and is getting fire on all cylindrs. i believe he removed each plug to see if it had fuel supply. The middle two cylinders on the passenger side had no fuel (plugs were dry). The odd part was following removal of the water in the tank it cranked and ran smoothly for a while then just died. Troubleshooting ever since. He checked grounds as well. He feels that the problem is related to the injectors but is not sure. It is odd that it will not start and run rough if that was the only issue, but I am not an expert on the C4.
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
QUOTE=C5nNC;1581898154]sorry for the lack of clarification. You are correct, it turns over but will not run. The garage I took it to replaced the distributor and is getting fire on all cylindrs. i believe he removed each plug to see if it had fuel supply. The middle two cylinders on the passenger side had no fuel (plugs were dry). The odd part was following removal of the water in the tank it cranked and ran smoothly for a while then just died. Troubleshooting ever since. He checked grounds as well. He feels that the problem is related to the injectors but is not sure. It is odd that it will not start and run rough if that was the only issue, but I am not an expert on the C4.[/QUOTE]
the two dry plugs may be the ones firing. if the others were wet it it likely running rich. this method is not a good method for checking fuel/air ratio, but if plugs are wet it won't always fire.
if you have a C5 you know where the FPR is. check the vac line to see if there is fuel spraying out when "cranking." I am assume it is too rich rather than too lean, from what you have said. locate a fuel presure gage and see what pressure it has and if it holds when key is off, for an hour or so.
ohm the injectors to see if one is shorted to ground. if it is, all injectors will fire constantly, flooding the engine.
even before that, hold WOT while cranking to see if it fires. verify that it is getting spark. unless the garage is competent, you need to verify the dist is installed correctly.
there are maybe 30 things that cause a no start, several pages in the fsm. do the simple things first.
the two dry plugs may be the ones firing. if the others were wet it it likely running rich. this method is not a good method for checking fuel/air ratio, but if plugs are wet it won't always fire.
if you have a C5 you know where the FPR is. check the vac line to see if there is fuel spraying out when "cranking." I am assume it is too rich rather than too lean, from what you have said. locate a fuel presure gage and see what pressure it has and if it holds when key is off, for an hour or so.
ohm the injectors to see if one is shorted to ground. if it is, all injectors will fire constantly, flooding the engine.
even before that, hold WOT while cranking to see if it fires. verify that it is getting spark. unless the garage is competent, you need to verify the dist is installed correctly.
there are maybe 30 things that cause a no start, several pages in the fsm. do the simple things first.
Last edited by joe paco; Sep 23, 2012 at 08:18 AM. Reason: italics
Thread Starter
Racer
Joined: Jun 2004
Posts: 252
Likes: 0
From: Brevard NC
UPDATE- first let me say this all started after car sat a while. I could drive car fine for 10 minutes and would skip a little then die and wouldnt restart. Took to shop and found the water in tank. They replaced and cranked right up and ran 10 minutes and back to square 1. Then new distributor due to no spark. Cranked great for ten minutes then same. If one if the fuel injectors was unplugged would crank and run and die immediately when plugged back in. Replaced 2 injectors and yes again cranked and ran fine for ten minutes then dies. Must be a timing or ecu problem killing spark or fuel at normal temp but no engine codes. Cant afford to keep replacing items that are only malfunctioning after the 10 minutes runtime. Any suggestions?
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
check ohms on injectors if this has not been done. unplugging to see if engine reacts is not the best way to discover a bad injector. all of them could be marginal. they are failing to shut off fuel most likely, not sure why the 10 mins. 02 sensor takes over at about 104*F.
if injectors are above 10 ohms, -about 16 is normal- they are not the root cause. monitor fuel pressure with a gage. these tests don't cost money, except for time.
"cranked for 10 minutes" ? you meant run, I guess.
** how are you checking codes, jumping the aldl connector under dash? when it dies, locate the MAP connector on pass side engine and unplug it, start and see the reaction. from the fsm, by the way.
if injectors are above 10 ohms, -about 16 is normal- they are not the root cause. monitor fuel pressure with a gage. these tests don't cost money, except for time.
"cranked for 10 minutes" ? you meant run, I guess.
** how are you checking codes, jumping the aldl connector under dash? when it dies, locate the MAP connector on pass side engine and unplug it, start and see the reaction. from the fsm, by the way.
Last edited by joe paco; Oct 2, 2012 at 08:21 AM. Reason: add**
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Thread Starter
Racer
Joined: Jun 2004
Posts: 252
Likes: 0
From: Brevard NC
check ohms on injectors if this has not been done. unplugging to see if engine reacts is not the best way to discover a bad injector. all of them could be marginal. they are failing to shut off fuel most likely, not sure why the 10 mins. 02 sensor takes over at about 104*F.
if injectors are above 10 ohms, -about 16 is normal- they are not the root cause. monitor fuel pressure with a gage. these tests don't cost money, except for time.
"cranked for 10 minutes" ? you meant run, I guess.
** how are you checking codes, jumping the aldl connector under dash? when it dies, locate the MAP connector on pass side engine and unplug it, start and see the reaction. from the fsm, by the way.
if injectors are above 10 ohms, -about 16 is normal- they are not the root cause. monitor fuel pressure with a gage. these tests don't cost money, except for time.
"cranked for 10 minutes" ? you meant run, I guess.
** how are you checking codes, jumping the aldl connector under dash? when it dies, locate the MAP connector on pass side engine and unplug it, start and see the reaction. from the fsm, by the way.
Burning Brakes
Joined: May 2011
Posts: 838
Likes: 2
From: Louisville Ky
it looks like a Manifold Absolute Pressure sensor. 
figured I should explain what it is.
the pic shows it to the right front of the gold plate, black rectangle, a green connector undeneath.
for clarity, if injectors ohm ok, it is not likely that they would suddenly leak after 10 minutes running. the best way to qualify injectors is by resistance test. is it actually 10 minutes?
also, are you checking codes by the SES display or by jumpering a-b terminals? if you need help on that, it's time to ask. if there are no codes, it means that it may not be a sensor.
figured I should explain what it is.the pic shows it to the right front of the gold plate, black rectangle, a green connector undeneath.
for clarity, if injectors ohm ok, it is not likely that they would suddenly leak after 10 minutes running. the best way to qualify injectors is by resistance test. is it actually 10 minutes?
also, are you checking codes by the SES display or by jumpering a-b terminals? if you need help on that, it's time to ask. if there are no codes, it means that it may not be a sensor.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
If it dies in 10 minutes, i would suspect closed loop operation.
i would just change the oxygen sensor because in open loop, the only sensor not used is the oxygen sensor.
i would also look for a bad vacuum hose to map sensor.
the other thing you might do is unplug the distributor, and look at both sides of the connector.
sometimes the wire terminals can get pushed out of their slots by someone pushing too hard and chipping away the plastic that holds the little tangs that holds the little blades in position
i would just change the oxygen sensor because in open loop, the only sensor not used is the oxygen sensor.
i would also look for a bad vacuum hose to map sensor.
the other thing you might do is unplug the distributor, and look at both sides of the connector.
sometimes the wire terminals can get pushed out of their slots by someone pushing too hard and chipping away the plastic that holds the little tangs that holds the little blades in position
