Modded my 85 vette...gas flow probs
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 16
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Modded my 85 vette...gas flow probs
Ok... I upgraded my 85 vette by ripping out all the old stuff. Putting in a new 383 stroker with a TPI mini ram. Had CPU upgraded for motor. I removed all catalytic converters and put in a 4" exhaust with Borla exhaust system. Problem I'm having is cold start she doesn't pop over right away(tested fuel pump and its at 44lbs psi). When warm and going down the road, if I get on the gas, sometimes she bucks and kicks before going like gas is not moving thru correctly. I'm lost guys, I am open to any suggestions on making performance better.
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
Who upgraded the CPU? Was it an off shelf program or someone did a "guess a tune" or was it a dyno tune?
What injectors were used? Assuming the motor is sound, have you done a fuel pressure check? I would take the hose off the FPR, cap off the nipple and do a WOT run and see if the pump will keep up.
What injectors were used? Assuming the motor is sound, have you done a fuel pressure check? I would take the hose off the FPR, cap off the nipple and do a WOT run and see if the pump will keep up.
Last edited by aklim; Apr 10, 2017 at 09:01 PM.
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 16
Likes: 0
Who upgraded the CPU? Was it an off shelf program or someone did a "guess a tune" or was it a dyno tune?
What injectors were used? Assuming the motor is sound, have you done a fuel pressure check? I would take the hose off the FPR, cap off the nipple and do a WOT run and see if the pump will keep up.
What injectors were used? Assuming the motor is sound, have you done a fuel pressure check? I would take the hose off the FPR, cap off the nipple and do a WOT run and see if the pump will keep up.
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
It was done by TPIS up in Minnesota. TPIS sold us mini ram and did the chip. I had a mechanic do a fuel pressure check. We couldnt figure it out. I am considering taking her in to be dyno tuned. I just wanted to make sure I havent missed something. Shes just a tune away I think from ripping it up.
This is where I got my work done.
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
Safety Car
Joined: Sep 2001
Posts: 4,160
Likes: 554
From: Glenbeulah Wi
Ok... I upgraded my 85 vette by ripping out all the old stuff. Putting in a new 383 stroker with a TPI mini ram. Had CPU upgraded for motor. I removed all catalytic converters and put in a 4" exhaust with Borla exhaust system. Problem I'm having is cold start she doesn't pop over right away(tested fuel pump and its at 44lbs psi). When warm and going down the road, if I get on the gas, sometimes she bucks and kicks before going like gas is not moving thru correctly. I'm lost guys, I am open to any suggestions on making performance better.
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Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 16
Likes: 0
What is your location? Should put that in the profile so we can see it and tell you where to go. In my case, they will tell me to go to hell.
This is where I got my work done.
This is where I got my work done.
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 16
Likes: 0
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
Thread Starter
Heel & Toe
Joined: Aug 2011
Posts: 16
Likes: 0
I myself am not a mechanic but helped my friend who is a mechanic do the engine upgrade.. I tinker here n there. My mechanic is a friend and ill relay your questions to him. So run a WOT test. Anything else(I'm praying your not going to say I need to drop the tank)?? I do have a Dyno test place not far from me. Would that help at this point?
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
You can drop the tank if you so desire but it isn't necessary to do that to get to the pump. Your call.
I wouldn't until we know for sure what the problem is and is fixed. It might be expensive to do there.
Team Owner
Joined: Sep 2001
Posts: 62,171
Likes: 1,735
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
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Fuel pump/pressure issue check first, as mentioned. Check at idle, bring the engine speed up and note behavior of the pressure. Kill the motor, see what it does then. Does it hold steady, how long, if not, how fast does it drop? This will point to pump, regulator, injectors depending.
2nd thing is the ECM/chip that was done. It needs to be tuned on a dynojet with a Wideband sensor, that will show the issue with the tune.
Either way it sounds like a not-enough fueling problem.
2nd thing is the ECM/chip that was done. It needs to be tuned on a dynojet with a Wideband sensor, that will show the issue with the tune.
Either way it sounds like a not-enough fueling problem.
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
Fuel pump/pressure issue check first, as mentioned. Check at idle, bring the engine speed up and note behavior of the pressure. Kill the motor, see what it does then. Does it hold steady, how long, if not, how fast does it drop? This will point to pump, regulator, injectors depending.
2nd thing is the ECM/chip that was done. It needs to be tuned on a dynojet with a Wideband sensor, that will show the issue with the tune.
Either way it sounds like a not-enough fueling problem.
2nd thing is the ECM/chip that was done. It needs to be tuned on a dynojet with a Wideband sensor, that will show the issue with the tune.
Either way it sounds like a not-enough fueling problem.
Safety Car
Joined: Nov 2009
Posts: 3,973
Likes: 341
From: Adelaide South Australia
as aklim and vader have said, you need to know things and check things before people on here can diagnose things.
what size are the injectors ? what is the fuel pump ? what size throttle body ? What is the actual fuel pressure ?
taking a wild punt I would say that a stock flow fuel pump on a 383 with a miniram just aint gonna cut it when you get on the gas !
what size are the injectors ? what is the fuel pump ? what size throttle body ? What is the actual fuel pressure ?
taking a wild punt I would say that a stock flow fuel pump on a 383 with a miniram just aint gonna cut it when you get on the gas !
Team Owner
Joined: Jul 2004
Posts: 28,495
Likes: 3,298
From: Hartford WI
as aklim and vader have said, you need to know things and check things before people on here can diagnose things.
what size are the injectors ? what is the fuel pump ? what size throttle body ? What is the actual fuel pressure ?
taking a wild punt I would say that a stock flow fuel pump on a 383 with a miniram just aint gonna cut it when you get on the gas !
what size are the injectors ? what is the fuel pump ? what size throttle body ? What is the actual fuel pressure ?
taking a wild punt I would say that a stock flow fuel pump on a 383 with a miniram just aint gonna cut it when you get on the gas !
Instructor
Joined: Sep 2016
Posts: 129
Likes: 16
From: Milwaukee WI
The fuel pump in our cars comes out in about 15 minutes. Open the gas door and remove the 4 torx screws, the door will then pull away with ease. If it's not clean, clean up the rubber area around the neck and remove the cap. Then carefully pry out the rubber. Remove the hoses and the 9 or so bolts, then the pump will lift right up. It'll take you 15 minutes to pull it out, maybe 30 if the hoses don't come off easy. So whatever you do, don't wait until the very end to check on the pump. :-D That said, I don't see why even a stock pump would have an issue supplying fuel to start the car. Though it could cause the other issues...
It might be worth finding out what base .bin they used for your chip. I had cold start issues once I removed the cold start injector on my 87. In theory TPIS knows about that and would have corrected for it though. Do you have any notes or receipts on what they did for the ECM?
*+1 on the WOT run
Last edited by slhawkins; Apr 11, 2017 at 09:18 PM.
