LOST 10mph AND ABOUT 6 TENTHS

[ss3011]

[[/QUOTE
Jeff This car use to be fuel injected and it still has the high pressure pump in it with regulator to knock down the pressure. regulator is set at 7.5 lbs also we dyno'd the engine and it still has the same power from when it was built[/QUOTE]

If the engine ran good on the dyno , then what parts are different between the car and the dyno ? Usually the dyno has it's own ignition box and it's own fuel system . Maybe check these two systems out to start with .

[Larry Hill]

Does the car have a timing retard box. I hade one go bad. I had the box checked, MSD said it was good. Hooked up box and car was slow, removed box and the car was fixed.

[Bill Marshall]

Originally Posted by ss3011

[[/QUOTE
Jeff This car use to be fuel injected and it still has the high pressure pump in it with regulator to knock down the pressure. regulator is set at 7.5 lbs also we dyno'd the engine and it still has the same power from when it was built

If the engine ran good on the dyno , then what parts are different between the car and the dyno ? Usually the dyno has it's own ignition box and it's own fuel system . Maybe check these two systems out to start with .[/QUOTE]

We took the coil and ignition box out of the car and ran it on the Dyno made good power

[ss3011]

Originally Posted by Bill Marshall

If the engine ran good on the dyno , then what parts are different between the car and the dyno ? Usually the dyno has it's own ignition box and it's own fuel system . Maybe check these two systems out to start with .

We took the coil and ignition box out of the car and ran it on the Dyno made good
power[/QUOTE]


So the only part that remained in the car and was not tested on the dyno was the fuel system . Not sure what type of pump or regulator you have , but the entire fuel system is in question including the fuel cell and any filters . Also check that the fuel cell has an open vent so the cell doesn't get a vacuum in it while the pump is running .

[Michael Compton]

Had a similar situation as this when I first started in Super Stock in 2007 or 2008. Ended up being the fuel pump. We had a Barry Grant fuel pump and regulator on the car and switched over to the Magnafuel units and all the problems went away. Mine would pop/bang on the big end like an electrical miss when in reality it was lean because of the fuel system. I was running a QJ at the time also.

[Stan Weiss]

Is the car down everywhere in the run or is the early part of the run still about the same?


Stan

[Adger Smith]

I forgot about the water pump. My V-6 is a Cam trigger and the magnetic pickup is on top, behind the water pump. I had a pump start leaking as we were loading the car. When we got to Ennis we made one run with a towel taped to the pump. It was leaking too bad so I took the Cheaper brand pump I carried as a spare and put it on. The car popped and missed at high RPM. We looked at plugs and ignition and all the electrical. We had one more shot of qualifying left and as I was doing my burn out the car popped on the chip... It hit me that the pump was what we changed and the problems cropped up. As I staged I turned the pump off. Good run, no 9000 RPM miss. Got back to the trailer and took the other pump apart and robbed the seal out of the electrical gremlin pump. Finished the race with no pump or miss problems. I figure that pump motor was a small radio station tuned to my ignition frequency. It wasn't playing any tunes my ignition liked...It seems like the simplest fixes can be the hardest!

[Lee Valentine]

Originally Posted by Adger Smith

I forgot about the water pump. My V-6 is a Cam trigger and the magnetic pickup is on top, behind the water pump. I had a pump start leaking as we were loading the car. When we got to Ennis we made one run with a towel taped to the pump. It was leaking too bad so I took the Cheaper brand pump I carried as a spare and put it on. The car popped and missed at high RPM. We looked at plugs and ignition and all the electrical. We had one more shot of qualifying left and as I was doing my burn out the car popped on the chip... It hit me that the pump was what we changed and the problems cropped up. As I staged I turned the pump off. Good run, no 9000 RPM miss. Got back to the trailer and took the other pump apart and robbed the seal out of the electrical gremlin pump. Finished the race with no pump or miss problems. I figure that pump motor was a small radio station tuned to my ignition frequency. It wasn't playing any tunes my ignition liked...It seems like the simplest fixes can be the hardest!

we had a bad ground on electric water pump slow us down one time.

[monte8616]

Originally Posted by Stan Weiss

Is the car down everywhere in the run or is the early part of the run still about the same?


Stan

Everywhere

[FED 387]

Try disconnecting the fuel line at the rear of the car blow it out with a low pressure air hose ---if you have a filter blow the line between rear of car and front of filter make sure its open ---then try from tank to before the filter with line disconnected--- from the rear to front try blowing from tank side of the filter thru the filter --- probably a clogged filter --if you do the 3 step method you will isolate where its "plugged"--- how old are the fuel lines in the car?? are they Aeroquip??? or stock??? if they are more than 2-3 years old might be time to replace them as the lining has maybe deteriorated -also check regulator for any obstructions ----FED 387