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Hey guys and gals! Maybe you can help me with this one, cuz it has me stumped!
Our van is a 91, 2WD, with the stock V-6 (217K miles on engine, 4K on rebuilt transmission), and TBI.
When we first got the van, it was running very rough, but it had 6 year old gas in the tank and a blocked cat. It would take 20-30 seconds to start, and would only start with the gas pedal depressed about half way. You would have to hold the gas pedal in for a few minutes while it warmed up, and then it would run, roughly, with hesitations and lag, and a cloud of white water smoke coming out of the exhaust, even though it doesn't loose any coolant...probably from the old gas, since it smelled so bad!
The first thing I did was put all new plugs and wires in it, a new cap and rotor, and found a fried water temp sender wire (the one that goes to the guage on the dash)...and I siphoned out all the old gas and filled the tank with fresh hightest fuel. The dash gauge started working fine, but there was no change in the way it ran or started!
Next I went to the timing. Checking it with the brown wire disconnected, I noticed it was advanced about 3 degrees. I brought the timing back to 0 degrees, and the van would barely run! No power at all, VERY serious lag, and wanted to stall on the test drive every time we stopped at a light or stopsign. So I brought it back to 3 degrees and it ran like it did before.
With the doghouse off and the aircleaner removed, watching the fuel injectors when it would start, it would take about 20 seconds for fuel to even start to dribble from the injectors, and that is exactly what it was doing at idle, just dripping into the TBI, although the fan/cone pattern seemed ok when you gassed it. And the fuel pump was VERY loud, so that was the next thing I did:
I dropped the fuel tank and replaced the pump...and the pickup sock, which was no longer see-through, but varnished dark brown from sitting in that old gas. Back the tank went in, and then a new fuel filter.
The results then? The fuel would still take about 20 seconds to start flowing from the injectors, but this time it actually flowed in a nice cone, and then with the pedal depressed, a nice even strong cone on both sides. It still took 15-20 seconds to start, you had to push the pedal down about half way to get it to start, and let it warm up so it would idle without stalling. There was still some lag driving it, but not nearly as much.
It would still smoke at startup, water vapor smoke for the most part, although the old gas smell was gone. So, I'm thinking the cat must be blocked.
Next I eliminated the cat with a 2 1/4" straight pipe flared to 2 1/2 inches to fit over the head pipe, with a new cylindrical muffler with 2 1/4 inch inlet and outlet, and reused the stock tail pipe, although I had the muffler shop repair the end of it where it plugs into the muffler, and used universal hangers in the stock locations...the result? No more smoke at startup (except a puff of oil smoke when you first start it up...hey, it has 217K miles on it, so its just a little puff from the valve guides), no more lag at all, more power than I thought these things could have, and runs great! EXCEPT....it still starts hard! 15-20 seconds! At least now it will almost start after about 15 seconds without pushing down the pedal, put to actually start it, you have to push the pedal half way down...and you still have to hold it at a higher idle for a minute or so before it will idle without stalling. Once it warms up a little bit, the idle is smooth, and the van runs great. Observing the injectors again, it doesn't get any gas spraying out for that whole 15-20 seconds that it won't start, and then once the gas starts spraying, it starts right up (with the pedal held down a bit)!
So, in summary:
No more cat, a new muffler, fresh gas after flushing the tank, new fuel pump and pickup screen, new fuel filter, new plugs and wires, new cap and rotor, new air filter, and a burnt temp sender wire repaired...
The results?:
It runs awesome now...except it still takes 15-20 seconds to start! And it will only start if you depress the gas pedal about half way! If you turn the key, it will catch and want to fire up after 15-20 seconds, but it won't start without pushing the gas pedal down. And then you have to hold the pedal down for a minute or so to keep the idle higher until it warms up a little, or it will stall. After about a minute or so, you can take your foot off the pedal, and she idles smooth. And it has all sorts of power now! No more lag in acceleration, no more skipping...and I think I have to bring the timing back down to 0 degrees, because now it seems to be idling a bit too high...if you are in gear at a stopsign or light, she wants to keep going! The transmission wants to keep on keeping on, so you have to shift it to neutral at a light or else the whole van vibrates.
That said, any ideas on why she is starting so hard?
The fuel pattern from the injectors on the TBI look great and even on both sides...although again, I did notice that when I start it without the doghouse or air cleaner in place, fuel doesn't shoot out of the injectors right away...it takes 15-20 seconds for the injectors to start spraying, and when they start spraying is when the engine finally starts.
It almost seems to me that something is telling the computer not to supply fuel right away for some reason...does it sound like any sensors you know about? Maybe the computer is getting a false code, telling it that the engine is already warmed up? By the way, she starts right up when the engine is at full warm-up...if you drive it for a while and then shut it down, she'll start right back up...once it cools down again, its hard start time again!
Oh yeah, the fuel pump runs constantly, although the new pump is quiet...is it supposed to run constant, or is it supposed to reach a certain pressure and shut itself off?
My next step is to remove the TBI, take it apart and clean it up, and then reinstall it...but I don't really thing this is the problem, since it looks spotless inside down the throats. I'm still thinking that since the fuel isn't getting delivered for that 10-15 seconds, it has to be one of the sensors...any idea which one/ones would do this?
Help me troubleshoot this please...lol!
Kev
Our van is a 91, 2WD, with the stock V-6 (217K miles on engine, 4K on rebuilt transmission), and TBI.
When we first got the van, it was running very rough, but it had 6 year old gas in the tank and a blocked cat. It would take 20-30 seconds to start, and would only start with the gas pedal depressed about half way. You would have to hold the gas pedal in for a few minutes while it warmed up, and then it would run, roughly, with hesitations and lag, and a cloud of white water smoke coming out of the exhaust, even though it doesn't loose any coolant...probably from the old gas, since it smelled so bad!
The first thing I did was put all new plugs and wires in it, a new cap and rotor, and found a fried water temp sender wire (the one that goes to the guage on the dash)...and I siphoned out all the old gas and filled the tank with fresh hightest fuel. The dash gauge started working fine, but there was no change in the way it ran or started!
Next I went to the timing. Checking it with the brown wire disconnected, I noticed it was advanced about 3 degrees. I brought the timing back to 0 degrees, and the van would barely run! No power at all, VERY serious lag, and wanted to stall on the test drive every time we stopped at a light or stopsign. So I brought it back to 3 degrees and it ran like it did before.
With the doghouse off and the aircleaner removed, watching the fuel injectors when it would start, it would take about 20 seconds for fuel to even start to dribble from the injectors, and that is exactly what it was doing at idle, just dripping into the TBI, although the fan/cone pattern seemed ok when you gassed it. And the fuel pump was VERY loud, so that was the next thing I did:
I dropped the fuel tank and replaced the pump...and the pickup sock, which was no longer see-through, but varnished dark brown from sitting in that old gas. Back the tank went in, and then a new fuel filter.
The results then? The fuel would still take about 20 seconds to start flowing from the injectors, but this time it actually flowed in a nice cone, and then with the pedal depressed, a nice even strong cone on both sides. It still took 15-20 seconds to start, you had to push the pedal down about half way to get it to start, and let it warm up so it would idle without stalling. There was still some lag driving it, but not nearly as much.
It would still smoke at startup, water vapor smoke for the most part, although the old gas smell was gone. So, I'm thinking the cat must be blocked.
Next I eliminated the cat with a 2 1/4" straight pipe flared to 2 1/2 inches to fit over the head pipe, with a new cylindrical muffler with 2 1/4 inch inlet and outlet, and reused the stock tail pipe, although I had the muffler shop repair the end of it where it plugs into the muffler, and used universal hangers in the stock locations...the result? No more smoke at startup (except a puff of oil smoke when you first start it up...hey, it has 217K miles on it, so its just a little puff from the valve guides), no more lag at all, more power than I thought these things could have, and runs great! EXCEPT....it still starts hard! 15-20 seconds! At least now it will almost start after about 15 seconds without pushing down the pedal, put to actually start it, you have to push the pedal half way down...and you still have to hold it at a higher idle for a minute or so before it will idle without stalling. Once it warms up a little bit, the idle is smooth, and the van runs great. Observing the injectors again, it doesn't get any gas spraying out for that whole 15-20 seconds that it won't start, and then once the gas starts spraying, it starts right up (with the pedal held down a bit)!
So, in summary:
No more cat, a new muffler, fresh gas after flushing the tank, new fuel pump and pickup screen, new fuel filter, new plugs and wires, new cap and rotor, new air filter, and a burnt temp sender wire repaired...
The results?:
It runs awesome now...except it still takes 15-20 seconds to start! And it will only start if you depress the gas pedal about half way! If you turn the key, it will catch and want to fire up after 15-20 seconds, but it won't start without pushing the gas pedal down. And then you have to hold the pedal down for a minute or so to keep the idle higher until it warms up a little, or it will stall. After about a minute or so, you can take your foot off the pedal, and she idles smooth. And it has all sorts of power now! No more lag in acceleration, no more skipping...and I think I have to bring the timing back down to 0 degrees, because now it seems to be idling a bit too high...if you are in gear at a stopsign or light, she wants to keep going! The transmission wants to keep on keeping on, so you have to shift it to neutral at a light or else the whole van vibrates.
That said, any ideas on why she is starting so hard?
The fuel pattern from the injectors on the TBI look great and even on both sides...although again, I did notice that when I start it without the doghouse or air cleaner in place, fuel doesn't shoot out of the injectors right away...it takes 15-20 seconds for the injectors to start spraying, and when they start spraying is when the engine finally starts.
It almost seems to me that something is telling the computer not to supply fuel right away for some reason...does it sound like any sensors you know about? Maybe the computer is getting a false code, telling it that the engine is already warmed up? By the way, she starts right up when the engine is at full warm-up...if you drive it for a while and then shut it down, she'll start right back up...once it cools down again, its hard start time again!
Oh yeah, the fuel pump runs constantly, although the new pump is quiet...is it supposed to run constant, or is it supposed to reach a certain pressure and shut itself off?
My next step is to remove the TBI, take it apart and clean it up, and then reinstall it...but I don't really thing this is the problem, since it looks spotless inside down the throats. I'm still thinking that since the fuel isn't getting delivered for that 10-15 seconds, it has to be one of the sensors...any idea which one/ones would do this?
Help me troubleshoot this please...lol!
Kev
