88 extended crank time - injectors?
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From: Harrisonburg VA
88 extended crank time - injectors?
I have a stock 88 with 96,000 miles. It starts right up the first time each day but after that it cranks 3-4+ seconds before starting. It seems to be flooded and the exhaust smells really rich. In fact it almost smells like raw gas right at first. It seems to perform well in every other way. I believe it has the original fuel injectors. Are they my culprit? I'm getting ready to change the intake gasket and am thinking this would be a good time for injectors.
Thanks for your help!
Thanks for your help!
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From: moraga ca
Fuel pressure regulator or injectors. Pull the vacuum hose to the regulator, see if it is filled with fuel. Check to see if the regulator holds vacuum with a mytivac. If the regulator is ok, then it must be a leaking injector or two
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From: Harrisonburg VA
OK, I just warmed the car up and let it set for 15 minutes. I checked the vacuum hose to the regulator and it was dry and there doesn't appear to be any sign that there has ever been any gas in it. I do not have a vac to check it but when I blow/suck on the hose there does not seem to be any leak. I tried to start the car immediately after this check and it did the same thing. Is this sufficient to rule out the regulator or should I get a mytivac before going for injectors?
Last edited by avgjoe; Mar 24, 2012 at 01:35 PM.
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From: Harrisonburg VA
I just read a post for an LT4 that had a similar issue and it ended up being the temp sensor. Could that be a possibility? It seems to read normally. I've never noticed anything out of the ordinary about the readings....
Racer
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From: Sierra Madre California
Had the same issue with my '88; it was the regulator. Next time you smell gas, immediately pull the throttle body and look into the plenum.
If there is raw gas in there, it is the regulator diaphram. Fairly easy fix; you can replece the diaphram without having to remove the regulator.
If there is raw gas in there, it is the regulator diaphram. Fairly easy fix; you can replece the diaphram without having to remove the regulator.
Racer
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Do a fuel PSI check. Fuel leak down fast or does it hold for awhile??
If it leaks down, FP check valve, injs or regulator is leaking down.
If it holds PSI, you could have a fuel pump relay going bad and its using your oil psi guage to send power to the fuel pump.
If it leaks down, FP check valve, injs or regulator is leaking down.
If it holds PSI, you could have a fuel pump relay going bad and its using your oil psi guage to send power to the fuel pump.
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From: Harrisonburg VA
Had the same issue with my '88; it was the regulator. Next time you smell gas, immediately pull the throttle body and look into the plenum.
If there is raw gas in there, it is the regulator diaphram. Fairly easy fix; you can replece the diaphram without having to remove the regulator.
If there is raw gas in there, it is the regulator diaphram. Fairly easy fix; you can replece the diaphram without having to remove the regulator.
I will get a fuel gauge and check if it is leaking down to quick. How long should it hold pressure after shutting the engine off? It seems like I have about 5 minutes or less and it will restart easy. After that it is a hard start and smells like gas.
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From: Overland Park Kansas
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So, your computer COULD think the engine is still cold. If true, you'd be running rich until it hits closed loop. Even then, it might not be able to compensate all the way. If you've noticed an overall drop in MPG, that could very well be your issue.
One sensor is in the front of the intake. The other down by the dipstick.
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From: Harrisonburg VA
OK, I checked the regulator and it holds vacuum fine. I did a fuel pressure test and here is what I found:
Turn on ignition and it pumps up to 44 psi and the fuel pump turns off. I start it up and it holds a steady 39psi at idle. When I remove the vacuum hose to the regulator it jumps to 44 psi and back to 39 when I reconnect. There is not gas in the regulator hose at any time. I ran it up to temperature and as soon as I turned off the ignition it sounds like the fuel pump continues to run for a second or two and the pressure goes up to 42 psi. It holds that pressure for about 6 minutes and here is where it goes from there:
8 minutes - 41 psi
10 min - 40psi
12 min - 38psi
14 min - 36psi
It continues to drop about a pound a minute for a while
38 min - 21psi
1 hr 40 min - 12psi and holding
I tried again and got similar results. Then I tried a restart at about 10 minutes with 40psi and it started hard and seemed flooded. It only runs rich for a few seconds until it clears out and then all is well. It just seems like fuel is getting in the intake or cylinders somehow after shutdown
What do you think? Is this a normal leak down or should it hold longer?
Turn on ignition and it pumps up to 44 psi and the fuel pump turns off. I start it up and it holds a steady 39psi at idle. When I remove the vacuum hose to the regulator it jumps to 44 psi and back to 39 when I reconnect. There is not gas in the regulator hose at any time. I ran it up to temperature and as soon as I turned off the ignition it sounds like the fuel pump continues to run for a second or two and the pressure goes up to 42 psi. It holds that pressure for about 6 minutes and here is where it goes from there:
8 minutes - 41 psi
10 min - 40psi
12 min - 38psi
14 min - 36psi
It continues to drop about a pound a minute for a while
38 min - 21psi
1 hr 40 min - 12psi and holding
I tried again and got similar results. Then I tried a restart at about 10 minutes with 40psi and it started hard and seemed flooded. It only runs rich for a few seconds until it clears out and then all is well. It just seems like fuel is getting in the intake or cylinders somehow after shutdown
What do you think? Is this a normal leak down or should it hold longer?
Last edited by avgjoe; Mar 31, 2012 at 10:27 PM.
Racer
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From: Carson City Nevada
I had similar readings with the same long crank times after warm up. When I pulled my plugs out 2 of them had a strong fuel odor. It turned out to be a leaky injector. Put in a set of rebuilt Bosch II's from FIC and the problem is gone. I am no Vette pro, but here is what I did to test the injectors. Remove the plenum and tubes. Remove all the bolts from the fuel rail and pull the injectors up out of the holes. Make sure your injector clips are installed correctly or one of them might pop out under pressure. Set them back in the holes (not all the way) and turn on the key to pressurize the fuel line. Do not crank the motor. Wait a minute and pop the injectors out of the holes and look for a drip. I only had 1 with a slow drip but it was enough to flood out the cylinder.
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From: SE NY
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To eliminate the cold start injector firing issue, pull the power to it and try a warm start; of course it could still be leaking.
To check for a leaking CS injector remove it and blank off the side of the intake as well as cap off the rear of the ruel rail.
To check for a leaking CS injector remove it and blank off the side of the intake as well as cap off the rear of the ruel rail.
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From: Harrisonburg VA
Thanks again!
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From: Harrisonburg VA
Today I unplugged the cold start injector and no change.
I also hooked it up to a scanner and the O2 sensor reading is lean for about the first 45 seconds. That doesn't make sense does it?
Also, even though it really acts like fuel is leaking into the cylinders/intake it doesn't make sense that it starts hard 5 minutes after shutting down and the fuel pressure has not dropped yet at that point...
I really want it to be the injectors because I probably need new ones considering the one I have are 25 yrs old and have 98K miles on them. On the other hand I don't want to throw $300 worth of parts at it either.
I also hooked it up to a scanner and the O2 sensor reading is lean for about the first 45 seconds. That doesn't make sense does it?
Also, even though it really acts like fuel is leaking into the cylinders/intake it doesn't make sense that it starts hard 5 minutes after shutting down and the fuel pressure has not dropped yet at that point...
I really want it to be the injectors because I probably need new ones considering the one I have are 25 yrs old and have 98K miles on them. On the other hand I don't want to throw $300 worth of parts at it either.
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From: SE NY
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Since you have a scan tool, does the scan coolant temp agree closely with that on the dash?
The O2 sensor will not read correctly, i.e. fluctuate, till after it's warm enough.
What do the BLM cells look like, i.e. is the ECM making reasonable corrections for correct A/F ratio?
Have you checked manifold vacuum? Do that at a warm idle.
The O2 sensor will not read correctly, i.e. fluctuate, till after it's warm enough.
What do the BLM cells look like, i.e. is the ECM making reasonable corrections for correct A/F ratio?
Have you checked manifold vacuum? Do that at a warm idle.
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Joined: Nov 2008
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From: Harrisonburg VA
Since you have a scan tool, does the scan coolant temp agree closely with that on the dash?
The O2 sensor will not read correctly, i.e. fluctuate, till after it's warm enough.
What do the BLM cells look like, i.e. is the ECM making reasonable corrections for correct A/F ratio?
Have you checked manifold vacuum? Do that at a warm idle.
The O2 sensor will not read correctly, i.e. fluctuate, till after it's warm enough.
What do the BLM cells look like, i.e. is the ECM making reasonable corrections for correct A/F ratio?
Have you checked manifold vacuum? Do that at a warm idle.
I was getting the lean reading on warm start up (205 degrees). Is it still not going to be right at first?
I have not checked manifold vacuum.
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From: Overland Park Kansas
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Check the resistance on the injectors when cold then HOT.
Use a volt-ohm meter and measure across the two injector contacts. It's a little trickier getting the injector plugs loose when it's hot, but doing it cold (first) will provide good practice.
I'm betting it is your injectors (coils). It would explain the lean condition and the hard restart.
Use a volt-ohm meter and measure across the two injector contacts. It's a little trickier getting the injector plugs loose when it's hot, but doing it cold (first) will provide good practice.
I'm betting it is your injectors (coils). It would explain the lean condition and the hard restart.
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From: Harrisonburg VA
New Injectors on the way
I spoke with Jon (FICINJECTORS) today and he is confident that my injectors are the issue given the symptoms, the fact that I have the original injectors and the car sat for 9 years. I ordered the new Bosch injectors that he is offering. Really nice guy (and a good salesman). Now I guess I will tear into it and get the intake gasket (leaking oil and some antifreeze) replaced while I wait for them to get here. If anyone has any tips on that project let me know. It doesn't look to difficult. Wish me luck 
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I'm sure they're needed too...especially with a 9-yr stabling.
Did you ever measure your current injectors? If so, why not?
FWIW, I recommend checking fuel pressure (using a free rental from AutoZone or similar). If you have any issue afterwards, it'll be really nice to know your baseline.
Measure with key-on, when running, and with the FP vacuum line removed.
Did you ever measure your current injectors? If so, why not?
FWIW, I recommend checking fuel pressure (using a free rental from AutoZone or similar). If you have any issue afterwards, it'll be really nice to know your baseline.
Measure with key-on, when running, and with the FP vacuum line removed.
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Instructor
Joined: Nov 2008
Posts: 169
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From: Harrisonburg VA
Did you ever measure your current injectors? If so, why not?
FWIW, I recommend checking fuel pressure (using a free rental from AutoZone or similar). If you have any issue afterwards, it'll be really nice to know your baseline.
Measure with key-on, when running, and with the FP vacuum line removed.
FWIW, I recommend checking fuel pressure (using a free rental from AutoZone or similar). If you have any issue afterwards, it'll be really nice to know your baseline.
Measure with key-on, when running, and with the FP vacuum line removed.
I did not test the injectors because I pulled the fuel pump to check the screen and broke one of the wires on the fuel sending unit and have not figured out how to fix it yet so I cannot run the car right now.
Is there anything that I can tell by just checking them cold?Jon pretty much sold me on the fuel injectors and I figure that if the injectors do not fix it they still needed to be replaced. Maybe I'm a sucker.
Last edited by avgjoe; Apr 6, 2012 at 10:48 PM.
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From: Overland Park Kansas
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I did measure the fuel pressure as mentioned and did a leak down test. See post #9 for the results.
I did not test the injectors because I pulled the fuel pump to check the screen and broke one of the wires on the fuel sending unit and have not figured out how to fix it yet so I cannot run the car right now. Is there anything that I can tell by just checking them cold?
Jon pretty much sold me on the fuel injectors and I figure that if the injectors do not fix it they still needed to be replaced. Maybe I'm a sucker.
I did not test the injectors because I pulled the fuel pump to check the screen and broke one of the wires on the fuel sending unit and have not figured out how to fix it yet so I cannot run the car right now.
Is there anything that I can tell by just checking them cold?Jon pretty much sold me on the fuel injectors and I figure that if the injectors do not fix it they still needed to be replaced. Maybe I'm a sucker.
If you don't know, they should measure around 16ohms across the coil (plugs). Section of the coils can short out but allow them to continue to "work" -- though not injecting sufficient fuel. When, it gets bad enough, you get a lean miss.
Mine wasn't exhibiting the same symptoms as yours though two were showing much lower resistance when hot....meaning sections of the coils would "short" as they got hotter. In my case, I wasn't getting much of a lean miss or hard starting because the two bad ones were on the O2 sensor side. When the O2 saw a lean condition, it pumped more fuel. You might have the bad ones (in majority) more on the passenger side of the motor.
Sorry, about forgetting about the FP thing. Sometimes, it's hard to remember what you read in each thread from one day to the next. Great that you have that "baseline"!
