944 race car fuel starvation right turns

race46 · 06-29-2016, 10:01 AM

944s race car sputters when fuel goes below half a tank -after hard right turn when full throttle is applied. I have read posts that the in-tank strainer/screen can be the problem - I replaced it. Checked the vent line that attaches to the sender that runs to the charc canister - seems fine.

I have pulled the sender unit from the trunk area and inspected in the tank a few times. I.m wondering about the plastic unit (think its called swirl unit) that sits above the screen. Does anyone know if there is a correct way (which way is front) for this to sit. Mine moved around and we put it back in roughly the same place then put the lid with the hole back on and put the sender down in.

I have completely drained the tank, fuel pump in fine, newish fuel filter etc. This only happens below half a tank on right turns.

any suggestions?

kdjones2000 · kdjones2000's Garage

You need a new fuel strainer at the bottom of the tank, PN 928-201-081-04.

http://www.pelicanparts.com/catalog/SuperCat/1021/POR_1021_FULFUL_pg3.htm#item11

We just ran a 924S (early tank) out at Willow Springs and it only started sputtering 3/4 of a lap before it completely died. We didn't even make it back to our pits.

dgcantrell · dgcantrell's Garage

I need to replace the one in the 88 S I've gotten back to running condition. Not because it's stopped up, it's because the thing is busted. I was changing the fuel pump out and stuck a long screwdriver into to check for crap in the tank. I gently put it in there a few inches but never felt any resistance at the end. It's like someone has jammed a screw driver in there and knocked the thing apart. I was going to remove it but the threaded bung embedded in the tank wants to turn with it. I'm afraid I'm going to have to remove both items to get it out to replace. Gluing the threaded bung back into the plastic tank is going to be fun. What should I use for that. JB Weld?

Rasta Monsta · Rasta Monsta's Garage

Quote:

Originally Posted by dgcantrell

I need to replace the one in the 88 S

Perfect time to ditch the steel tank and go plastic.

race46 · 06-29-2016, 12:57 PM

i already have replaced the screen and the car has a newer plastic tank

Any other ideas?

Rasta Monsta · Rasta Monsta's Garage

When my race car was doing that it "fixed itself". . .I figured it was a clog in the crossover tubes that allow fuel to go from the left to the right compartment in the tank, and that it cleared. The car used to do it with 3-4 gallons remaining, now it can run down to near dry without doing it.

por944s2 · por944s2's Garage

This is probably why, on right turns your car has fuel delivery issues. With the top of the baffle no longer connected to the bowl, fuel can spill out and over the "bowl". Now if I cold only get a hand down the hole to re-attach the top.

DarrenD · 02-04-2018, 06:54 AM

I have this same issue on my track car -86 944 turbo.

What is that a picture of?^^

kdjones2000 · kdjones2000's Garage

The whitish thing down at the bottom is the fuel strainer.

What he is saying is that there is an "upside down" bowl at the bottom of the plastic tanks that contains the fuel strainer and the final bit of fuel in the tank.

In this case, the top of that bowl has come off, allowing the fuel to escape the enclosure and let air into the strainer/fuel lines. This leads to cavitation, low fuel pressure and bogging down when coming off turns when your fuel level is low.

This is the first I have seen this, but it's a nice find - just hard to correct short of buying a new fuel tank.

DarrenD · 06:29 PM

Anybody else have this issue? I chased this all last year and short of driving around with a full tank all the time I'm not sure what else to do. I looked inside my tank but don't seem to have the same issue. What else could it be?

I've replaced the fuel pickup strainer but the old one was in fine condition so I doubt that it was causing the issue.

A friend suggested we stuff the tank full of fuel cell foam, I didn't know what to say to that...

The problem seems to start at approx. 5/8-3/4 full tank and under hard braking before a hard right turn. Obviously the fuel is sloshing away from the pickup screen, but why all of a sudden? What has changed inside the tank to cause this?

Thanks for any help you can provide.

kdjones2000 · kdjones2000's Garage

Sounds like a different issue for you.

This one happens while at the end of a long right hand turn, or exiting that corner. Not on braking. It also tends to happen at around 1/2 a tank or less.

You may be losing some electrical connection while hard on the brakes... I doubt it is fuel, more electrical, possibly leading to fuel.

DarrenD · 03-15-2018, 02:44 PM

Quote:

Originally Posted by kdjones2000

Sounds like a different issue for you.

This one happens while at the end of a long right hand turn, or exiting that corner. Not on braking. It also tends to happen at around 1/2 a tank or less.

You may be losing some electrical connection while hard on the brakes... I doubt it is fuel, more electrical, possibly leading to fuel.

Yes, that's when it happens. When I brake hard, turn in and get back on the gas, it sputters in right hand turns. Doesn't happen with a full tank.

Timmay! · 04-01-2018, 05:16 PM

Had a similar issue in an 87 944 Spec car. Engine would cut out AFTER, not during, hard right hand turns. It was the ignition switch going bad and cutting power to the fuel pump while pulling the g's. Engine would cough and sputter when coming onto the next straight, then run like a raped ape. Fast.

Timmay! · 04-01-2018, 05:18 PM

Cantrell, we epoxied the tank strainer sleeve back in and it's been fine for yrs.

zzwhm · 11-12-2019, 07:16 AM

Quote:

Originally Posted by Timmay!

Cantrell, we epoxied the tank strainer sleeve back in and it's been fine for yrs.

Timmay!

How did you manage to get access to epoxy the strainer sleeve?

I have exactly the same problem with he bowl at the bottom of the tank having come loose.
Bill

Timmay! · 11-12-2019, 12:08 PM

Bill, I think the plastic bowl snaps into place?

RE: the epoxy deal. The threaded sleeve came out with the strainer. It just pulled out of the tank. We roughed up the inside of the tank sleeve hole. Then epoxyed the threaded sleeve back into place, then screwed the strainer back in.

zzwhm · 11-13-2019, 10:06 AM

Quote:

Originally Posted by Timmay!

Bill, I think the plastic bowl snaps into place?

RE: the epoxy deal. The threaded sleeve came out with the strainer. It just pulled out of the tank. We roughed up the inside of the tank sleeve hole. Then epoxyed the threaded sleeve back into place, then screwed the strainer back in.

Thanks, Timmay!

I plan to drain the tank and see if I can get the the plastic bowl back together and to stay in place. My strainer is pretty new but I will also take a look to make sure it's ok.

Bill

Timmay! · 11-13-2019, 05:36 PM

Here to serve the 944 community.

I'm a smaller man, and as such, I can get much of my arm down inside the late model gas tank. Hope you can too.

zzwhm · 11-15-2019, 05:36 PM

I drained my tank today and took out the fuel level sender. When I looked in the tank the bowl pictured in the post above was just rolling around loose in my tank.

The top of my bowl was attached. But the bowl wasn't at the bottom of the tank where it should have the fuel pickup filter going in the side and the fuel level sender in the top. I tool out the fuel filter, re positioned the bowl with the filter and sender in their respective holes.

I'm optimistic this will solve the fuel starvation issue. I'll report after I get it on the track.

bxfe · 04-05-2022, 05:32 AM

My 944S2 racecar did this again at Sebring Sunday. Exactly like last time......1/2 tank of fuel, long right under bridge, engine died, was able to restart Just before the hairpin. On the advice from this thread, I’d just replaced the fuel pump, tank strainer and lines from tank to pump. Thoughts on next causes to chase? IGN switch? Canister & it’s lines? Fuel pump harness?