Still running terrible


Jul 26, 2023
About to do the old fuel upgrade. Fuel pump. Hot wire. Filter, injector. Regulator, TT Chip. Hoping this will solve or help. The car start runs decent for 10 seconds. Then misses, chokes and sputters eventually stalling. I have spark, plugs are black and seems to be running fat based on smell and smoke. All Scanmaster points seem fine but I feel it’s not running long enough to get good reading. Any thoughts before I dig into this tomorro. 87 GN, supposed to be about 40k miles however has been sitting for a number of years.
" however has been sitting for a number of years."
What's a "number of years"?
What did you do prior to starting the first time?
Sounds to me as tho you are going to perform all the necessary items after the fact.
A spring cleaning is in order.
MAF sensor might be suspect as well. Try tapping on it while the car is running. How long does it run before dying?
The car start runs decent for 10 seconds. Then misses, chokes and sputters eventually stalling
Put a temporary fuel pressure gauge on the rail. Cycle the key or power the pump at the test terminal and see what the pressure goes to, how long it takes to make pressure, how long before it bleeds off, or just run it and see if the pressure is dropping as it dies. Filter, pump and sock, regulator, all need to be replaced anyway.
My car had been sitting for about 13 years, the pump barely made 60 lbs, and got there slowly, the filter sock was hard and crispy, the filter was mostly clogged, and the regulator diaphragm was hard.
You need to replace all of these anyway, but you can pull the pressure line off of the regulator, run it into a can, and visually look at the flow, if it makes you feel better, before you replace all of that stuff.
If the fuel system makes pressure, but not volume, and isn't the main problem right now, you will lean out and kill what's left of the engine anyway. Just sayin'.
Thanks Chuck. Funny thing is I actually have an eye doctor's appointment coming up, first time in my life I've needed glasses!
Mine hit at 40. Wore them for another 40.. Got the "fix" and no more glasses...Really close up, a pr of 1.5's from Wallyworld.
Update…… replaced fuel pump, line, filter, injectors, regulator. Had to change plugs as the new plugs had already fouled. Car now starts, runs, but a little. Took it for a little drive and it coughs a bit when on the the throttle with black smoke coming out the exhaust. Running rich I assume. Have a fuel pressure gauge on order. I’m thinking the pressure is too high. Question for now until I get the gauge is I have error code MAF sensor low/high coming up on the scan master #33 and 34. What is your thoughts on these?
Thanks for all the help folks.
Make sure your chip matches everything. You changed injectors, do they match the chip? Are your translator settings correct? The ECM needs time to learn after changes have been made.

What are your other Scanmaster numbers? AF, IAC, TPS, etc.

Here is some code troubleshooting tips.

You did reset the computer after the changes, didn't you? Ya know, disconnect from the battery for 30 sec. Or so?
Yes everything matches bought as a package. Everything on the Scanmaster seems in range. I will look more closely today. Thanks