13 replies to this topic

[Speedycrw]

Had a great few races this weekend, car ran fine, until Sunday in my third race, my engine started sputtering in corners. Initially, it was tiny sputters, eventually working to what seemed like fuel cut outs. I barely made it in to the pits when it occurred the last time. With the accelerator to the floor, the motor seemed to be just barely firing, once I finally made it to the paddock area, the motor ran fine. I have an AFR meter but, didn't think to look at it during this incident, so I can't provide input to whether it is fuel delivery or ignition related. The car runs fine now around the paddock, on and off the trailer and at idle and being revved.

I can basically only throw "fixes" at it. I plan to replace the fuel filter, drain the gas in the tank(yes it had 1/4 of a tank)and replace with new, check the canister to see if it is full of gas, maybe replace the CAS and Ignition coils, double check and/or replace plug wires( I already have them. Are there any other possible "quick" fixes that might address the issue? I have an event this weekend and don't have the luxury of a complete diagnosis session at a track....just able to do quick "possible" fixes.

The car is a 1995, Stewart Motor, and it has 40 races on the bottom end and 15 races on the head..... Any other ideas+fixes?

Thanks in advance!

[Bruce Wilson]

I had one of those rubber fuel jug gaskets break up and go into the tank where it quickly disolved. It plugged up the fuel pump screen and caused the same type of issue. The car would stumble coming out of corners so I thought it was g-force related, but it was actually acceleration related (and coming out of corners is where that occurs). I pulled the fuel pump and replaced the screen and cleaned all the remaining debris and all was better.

-bw

[Keith Novak]

I had this happen a couple weeks ago, probably a bit worse than what you're describing in my '95. Despite hours of many people poking things, checking all sorts of connections and such we never found the gremlin but we got it to stop. Best case scenario is you find something came loose, hook it up and you're good.

Check the easiest things first.

I would check your grounds because I've seen a lot of problems where the engine intermittenly cuts out caused by grounds. One friend chased it down to the one on the back of the intake after a few frustrating weekends. Check them all. PPF, intake, the little bracket on the front, the big one by the brake booster... I cleaned and put the little star shaped washers under all mine but it didn't fix my problem.

Air restrictions were the next suspect. Many people have left rags in things or found mice set up home in the airbox on short notice. A 5 minute job to pull all the air lines off the front and filter to check for rodents and old socks.

I then went to the diagnosis part of the manual. The AFR attached to the throttle body is an easy check. Pop the plug and check the resistance. That didn't pan out for me but it's an easy check.

We were able to duplicate the cut out by raising the rear end and I reved the motor with my foot on the brake since it only cut out about 3500 under load. It died.

We then dumped the fuel. Reloaded it, checked fuel pressure at idle, and did the ghetto dyno again while checking fuel pressure. Pressure was good, the problem stopped and hasn't reoccured so I'm guessing bad fuel, a bit of crud worked its way through the system, or the tea bag attached to the fuel pump was clogged and fresh gas washed it off.

Going through the diagnostics, plugs and wires come up over and over but mine were pristine so I ruled that out. The coil was a viable candidate as agreed to by the many people looking and poking so I was ready to swap it with a spare. Without getting into the fuel tank, the fuel filter is easily accessible (mine was new) but I also had a complete fuel rail handy, and I had a reliable throttle body on hand with the associated electrical widgits. If it hadn't fixed itself, the next step to racing rather than cursing and wrenching all weekend was rail, throttle body and coil (with a CAS thrown in because it's there).

Beyond that, it's electrical which is pure evil as far as I'm concerned.

[Funracer]

Had a great few races this weekend, car ran fine, until Sunday in my third race, my engine started sputtering in corners. Initially, it was tiny sputters, eventually working to what seemed like fuel cut outs. I barely made it in to the pits when it occurred the last time. With the accelerator to the floor, the motor seemed to be just barely firing, once I finally made it to the paddock area, the motor ran fine. I have an AFR meter but, didn't think to look at it during this incident, so I can't provide input to whether it is fuel delivery or ignition related. The car runs fine now around the paddock, on and off the trailer and at idle and being revved.

I can basically only throw "fixes" at it. I plan to replace the fuel filter, drain the gas in the tank(yes it had 1/4 of a tank)and replace with new, check the canister to see if it is full of gas, maybe replace the CAS and Ignition coils, double check and/or replace plug wires( I already have them. Are there any other possible "quick" fixes that might address the issue? I have an event this weekend and don't have the luxury of a complete diagnosis session at a track....just able to do quick "possible" fixes.

The car is a 1995, Stewart Motor, and it has 40 races on the bottom end and 15 races on the head..... Any other ideas+fixes?

Thanks in advance!

I heard of a similar thing last year. Turned out a plate had come loose
inside the battery and would short out in the corners as it moved around.
Swap the battery with one from another car to check it out.

Good luck. The list of possible culprits here is long.

Neil

[Caveman-kwebb99]

Chris, Ihad this exact problem last year at Putnam. it started little and got worse and worse, it happened alot in turn 9-10. I was told to change out my entire fuel pump system in the tank wich I did the part was about 350.00 but fixed the problem right away. Best of luck.

[rmgroth]

How old is the gas tank?

I have seen a couple older cars that have had one of the baffles in the tank come loose and block the pickup. Just fixed one of these a couple months ago.

The baffles are only tacked in and over the years of racing/vibration/etc seem to cause them to fail.

If you pull the fuel pump you can probably feel around in there and check it, or if its like the couple I have seen you wont be able to remove the pump because the baffle is wedged in place, so you have to get a little creative. Just a thought.

Ryan Groth
#52 SM
NASA Midwest SM Series Director

[Speedycrw]

Thanks so much for all of the insights guys, I hadn't thought of quite a few of them... I have a lot of possiblities to try in the next few days! if anyone else has stories/ideas, please let me know! I'll report back after the weekend or when I find the problem....

[trey]

I had a similar issue at TWS a couple of weeks ago in the 1st session of the weekend ... The electrical system shut off in all the right hand corners. ( I knew it was electrical because the after market electric gauges went off when the car was loaded and picked back up when unloaded )

I came in , unbuckled , pulled on the wiring harness under the passenger side dash , buckled back up and got 2 laps before it came back

After the session I undid all the racers tape the previous owner had applied to hold up the wiring harness and replaced the support with tie wraps.

The car ran perfectly all weekend after that ... I guess there is a broken connector or short somewhere in there

[Speedycrw]

AND WE HAVE A WINNER!!! Mr. Groth step up you guessed correctly..... the baffle in the tank had come loose.... I can only pull it and run without it right now..... guess I will have to run more gas this weekend... how did you fix it? did you have to pull the tank and weld back in place or did you just run without it?

Thanks for all the suggestions guys!

Chris

[Dennis]

I had a baffle break loose in my 94. Car ran fine but the fuel gauge would "stick" and stop changing as fuel was added or consumed, then after a while it would work again then another stick........ I opened it up to replace the sender and found the broken baffle. Replaced the tank with new.

Dennis

[Funracer]

AND WE HAVE A WINNER!!! Mr. Groth step up you guessed correctly..... the baffle in the tank had come loose.... I can only pull it and run without it right now..... guess I will have to run more gas this weekend... how did you fix it? did you have to pull the tank and weld back in place or did you just run without it?

Thanks for all the suggestions guys!

Chris

Thanks for reporting the fix. I hate when you read a long thread about
a problem and then it just ends without anyone knowing the cause.

Regards

[Brandon]

AND WE HAVE A WINNER!!! Mr. Groth step up you guessed correctly..... the baffle in the tank had come loose.... I can only pull it and run without it right now..... guess I will have to run more gas this weekend... how did you fix it? did you have to pull the tank and weld back in place or did you just run without it?

Thanks for all the suggestions guys!

Chris

Chris,
Which direction turns would it cut out on you? I experienced the same thing this past weekend with over a half-tank of gas but it was with left-hand turns which would be opposite of a fuel starvation scenario (which I have experienced).

I may be hitting the down yonder salvage yard for a fuel tank...bringing my hefty jack/stands to lift the things out of the dirt & grass!

Thanks,
Brandon

[Speedycrw]

Brandon,

The car cut out on both left and right handers, and finally would hardly run even on a straightaway. When I took the fuel pump out of the tank, it was difficult to remove as it was tied up with the loose baffle. The baffle was cut and shaped sheet metal about the size of a sheet paper with several holes cut in it. I had to use tin snips to clip and remove the baffle from the tank. The fuel pickup(sock) rests in a smallish reservoir that should provide some protection against starvation... I have a line on a preplacement tank.... Hope this helps

Good luck!

Chris

[Keith Novak]

Interesting. I need to check mine now. It would make sense when I think about when mine started acting up, and when it stopped.