LT1 Sonoma help
Thread Starter
Teching In
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LT1 Sonoma help Hi guys, this is my first post here, so let me introduce my project---
1995 GMC Sonoma with a stock '97 LT1/T56.
I had the motor in it for awhile, then I wrecked the truck(long story-immaturity and a bad temper). I have since been rebuilding it (new frame, curvy road parts, etc.). When the motor was in it before, it had a few rough running problems but nothing too major, I never had a chance to have it fully tuned.
Now I have it running again and it has a problem, it will idle fine and when in reverse with no feet on the pedals it will go. When you give it any gas at all it starts running rough with a strong gas smell and dies, it seems to me like it may be flooding?
The only thing that is different with the actual motor setup is the fuel system, which consists of an Aeromotive A1000 and a 16 gallon fuel cell. I had considered the option that the pump may be too much and I might need an adjustable pressure regulator, but I was told the stock one should still be enough to do the job.
The motor was sitting for about a year and a half with only periodic starts.
Does any one have an opinion on what this problem might be?
In the very near future I would like to get a laptop and the proper cables and try to learn how to do some of the tuning myself.
Thanks in advance for any help,
carson
1995 GMC Sonoma with a stock '97 LT1/T56.
I had the motor in it for awhile, then I wrecked the truck(long story-immaturity and a bad temper). I have since been rebuilding it (new frame, curvy road parts, etc.). When the motor was in it before, it had a few rough running problems but nothing too major, I never had a chance to have it fully tuned.
Now I have it running again and it has a problem, it will idle fine and when in reverse with no feet on the pedals it will go. When you give it any gas at all it starts running rough with a strong gas smell and dies, it seems to me like it may be flooding?
The only thing that is different with the actual motor setup is the fuel system, which consists of an Aeromotive A1000 and a 16 gallon fuel cell. I had considered the option that the pump may be too much and I might need an adjustable pressure regulator, but I was told the stock one should still be enough to do the job.
The motor was sitting for about a year and a half with only periodic starts.
Does any one have an opinion on what this problem might be?
In the very near future I would like to get a laptop and the proper cables and try to learn how to do some of the tuning myself.
Thanks in advance for any help,
carson
Thread Starter
Teching In
Joined: Mar 2007
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The only mods done to the motor are headers, other than that it is completely stock.
The pump puts out about 90psi, I think. LT1s should have about 45psi right, is the stock regulator just to weak to handle that much? I'm not against putting an adjustable regulator on it, I would just like to know if that would solve the problem or not.
How could I put a pressure gauge on it as is to check? The aeromotive regulator has a port for a gauge doesn't it?
Sorry for all the newbie questions, but I'm trying to learn.
The pump puts out about 90psi, I think. LT1s should have about 45psi right, is the stock regulator just to weak to handle that much? I'm not against putting an adjustable regulator on it, I would just like to know if that would solve the problem or not.
How could I put a pressure gauge on it as is to check? The aeromotive regulator has a port for a gauge doesn't it?
Sorry for all the newbie questions, but I'm trying to learn.
Originally Posted by carson
The only mods done to the motor are headers, other than that it is completely stock.
The pump puts out about 90psi, I think. LT1s should have about 45psi right, is the stock regulator just to weak to handle that much? I'm not against putting an adjustable regulator on it, I would just like to know if that would solve the problem or not.
How could I put a pressure gauge on it as is to check? The aeromotive regulator has a port for a gauge doesn't it?
Sorry for all the newbie questions, but I'm trying to learn.
The pump puts out about 90psi, I think. LT1s should have about 45psi right, is the stock regulator just to weak to handle that much? I'm not against putting an adjustable regulator on it, I would just like to know if that would solve the problem or not.
How could I put a pressure gauge on it as is to check? The aeromotive regulator has a port for a gauge doesn't it?
Sorry for all the newbie questions, but I'm trying to learn.
TECH Apprentice
Joined: Mar 2006
Posts: 326
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Originally Posted by MEAN LT1
90psi is way too much, stock FP should be around 39-41 psi at idle with the vacume tube plugged in. I would work on getting that strait and go from there. But it does sound like your fp regulator is bad.
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From: Evansville, IN
Stock 93's have a schrader valve on the drivers side of the intake manifold in the fuel line. Not sure if it is in the same spot in later models or not. Check that fuel pressure. I would say that is your problem.
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well, since all of the shops in town decided to take a vacation on the same week, I haven't been able to borrow a fuel pressure gauge. But today I had a thought to pull the vacuum line off of the stock FPR and see what happens...
it runs almost perfect, it has a slight but steady miss but I'm sure the plugs are fouled from sitting so long and from the recent problem, and it only has open headers with about two feet of pipe still hooked up. as long as the vacuum is unhooked it runs, as soon as you hook the line back up and goose a little it starts to bog down and die. Leaving the vacuum line unhooked isn't a permanent fix, I wouldn't think, but maybe it will shed some light on whats going on.
it runs almost perfect, it has a slight but steady miss but I'm sure the plugs are fouled from sitting so long and from the recent problem, and it only has open headers with about two feet of pipe still hooked up. as long as the vacuum is unhooked it runs, as soon as you hook the line back up and goose a little it starts to bog down and die. Leaving the vacuum line unhooked isn't a permanent fix, I wouldn't think, but maybe it will shed some light on whats going on.
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So could it be that it the stock FPR isn't letting enough gas in? Even with the vacuum unhooked it isn't drivable. It responds in the same way, only going in reverse (which is a little strange and I'm not sure of the connection). Although with vacuum unhooked it seemed to make it longer going forward, like whatever the problem is it delayed.
Thread Starter
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I've come up with a few possibilities and I just wanted to throw them out and see what yall thought:
1. could it be that the pump isn't getting enough voltage?
2. it could possibly be a clogged fuel filter, this is the first time it has ran with the new cell.
3. the pump could be bad, it is brand new, but stranger things have happened.
4. the stock FPR is bad, how common would this be, and if it was bad wouldn't it be doing the opposite and letting way too much gas in?
I appreciate all of the help from you guys so far, I'm ready to get this thing back on the road.
1. could it be that the pump isn't getting enough voltage?
2. it could possibly be a clogged fuel filter, this is the first time it has ran with the new cell.
3. the pump could be bad, it is brand new, but stranger things have happened.
4. the stock FPR is bad, how common would this be, and if it was bad wouldn't it be doing the opposite and letting way too much gas in?
I appreciate all of the help from you guys so far, I'm ready to get this thing back on the road.
