Fuel Problems

[GMCSyclone1]

I went up to the Nascar races this weekend in Dover and I noticed a few problems on the way back. First my abs light came on but when I checked the brake fluid it was basically dirt so I am gonna change that out and hopefully it will solve that prob. The real problem I'm having is that the truck wants to die out whenever I smash on it. If I ease on the throttle it takes off fine but once the pedal goes to the floor the truck starts to sputter like the fuel is being cut. I noticed it the first time at about 40 to 80 around 80 it started to sputter it did the same when I floored from 80. I decided to smash it once from a stand still and once from a launch both times same issue truck takes off then its like the fuel cuts on me. I just installed a Walbro 255 and I had over a half of tank so I doubt its a fuel slosh prob. especially since it does it from a roll aswell. I don't know if it is something in the ECU or if its a boost problem. I'm not sure exactly where to look first. Does anybody have any ideas? Thanks for any help.

 

[GMCSyclone1]

Re: Fuel Problems

Any ideas? :dunno: I'm hoping to get the problem fixed before this weekend there is supposed to be a big show up in Ocean City MD.

 

[LBoogie]

Re: Fuel Problems

Maybe replace the fuel filter?

 

[SY2932]

Re: Fuel Problems

Don't rule out the ignition on these trucks... I had a similar problem this summer and it ended up being a combination of a weak ignition coil and semi bad coil wire that only manifested itself while under heavy load. Likewise, I suspected that it was a fueling problem at first especially since my Walbro pump is getting old. I connected my mechanical fuel pressure gage (used for setting fuel pressure) and secured it up near the cowl (removed hood for this test) so that I could observe what was ACTUALLY going on with my fuel pressure when it cut out. At no point did the pressure drop and it was rock solid when the cut outs occured=not a fuel problem. A weak ignition won't have the energy to ignite the air/fuel mixture under heavy load especially when boost that is trying to blow the spark out is added to the equation. Just something else you can look into.

 

[GMCSyclone1]

Re: Fuel Problems

Ok this is weird I had the Sy out today after changing the brake fluid and bleeding them. Which didn't solve my problem with the anti lock and brake lights being on. Does anyone have a any schematic diagrams of the brake system I'm guessing it is a dirty or bad sensor. Any suggestions? Anyways back to the weird part I took the Sy out and did a few launches and stomped on it going down the road the truck never bogged once. I mean one day I can't get on it at all and the next its running like new. I don't get it :dunno: but I'm not gonna complain hopefully it stays that way. Can't tell if the truck is running 100% though but it seems a lot better than it was hopefully a run before the tracks close will let me know.

 

[GMCSyclone1]

Re: Fuel Problems

I took the Sy out for a little ride tonight and its bogging again.:banghead: Just out of curiosity could it be overboost causing the fuel to cut? I haven't forgotten about an ignition prob. but I'm just wondering if it could be overboost. I still only have the stock boost gauge but when I get on the throttle it shoots way past 15, I'm not sure where a stock gauge spikes at I can't see it being real accurate but could this be my prob?:dunno:

 

[SY2932]

Re: Fuel Problems

but I'm just wondering if it could be overboost. I still only have the stock boost gauge but when I get on the throttle it shoots way past 15, I'm not sure where a stock gauge spikes at I can't see it being real accurate but could this be my prob?:dunno:

I figured that these trucks have been around and modified enough by now that EVERY truck has an aftermarket boost gauge in it. Guess not :squint: ... Overboosting is VERY bad for the motor, keep overboosting and you won't be doing it for long. The fuel cut off is the trucks way of telling you that you have a serious problem and it is trying to keep you from blowing the motor. Oh and another thing, overboosting is VERY bad for the motor. The first thing you should check is to make sure that the wastegate is functioning properly because overboosting is VERY bad for the motor.

 

[GMCSyclone1]

Re: Fuel Problems

So what your trying to say is overboosting is very bad for the motor! I get that I just wasn't sure if that was my problem or not and how accurate the boost guage is at telling me if I'm overboosting. I figure if its shooting up past 15 then it was but I was just trying to look at every angle of this problem. Thats really the first time I noticed the boost guage shooting up so high.

 

[GMCSyclone1]

Re: Fuel Problems

The first thing you should check is to make sure that the wastegate is functioning properly because overboosting is VERY bad for the motor.

On that note thanks for the info. My truck is bone stock other than the Walbro now this is probably a dumb question but could the header wrap possibly be the reason for the wastegate not functioning properly?

 

[SY2932]

Re: Fuel Problems

Exactomundo ! Boost plus the AWD (in addition to the rarity) is what makes sytys unique. No boost=no high performance. Since boost is the "life blood" of any syty, is it *imperative* that you have a way to monitor it. If you want to forgo all the "tried and true" mods like a Walbro FP, AFPR, heater hose IC lines, hardwired IC pump etc., etc. so be it. At the very LEAST you should consider a mechanical boost gauge. It is A LOT cheaper than a new motor...

 

[GMCSyclone1]

Re: Fuel Problems

Exactomundo ! Boost plus the AWD (in addition to the rarity) is what makes sytys unique. No boost=no high performance. Since boost is the "life blood" of any syty, is it *imperative* that you have a way to monitor it. If you want to forgo all the "tried and true" mods like a Walbro FP, AFPR, heater hose IC lines, hardwired IC pump etc., etc. so be it. At the very LEAST you should consider a mechanical boost gauge. It is A LOT cheaper than a new motor...

No by all means I love my Sy and care for it like a its my kid. I just don't have a lot of money at this point but if I didn't care about it I wouldn't have spent the summer undercoating it and working under the hood. I have the Walbro, Heater Hose IC Lines, I haven't done the IC pump hardwire yet and I can't afford a AFPR or a boost guage at this point. I just want to get to the bottom of my prob.