Cuts out under boost

[Quatro]

93 Ty stock 37,000 miles. Idles smooth and runs perfect until you stand on it. Then it cuts out but does not throw any codes. New cap, rotor, wires, plugs, fuel filter, PC valves, air filter. Replace 2 vac lines and does not seem to have any leaks. I do not have datamaster.
Any ideas appreciated. Also, does not cut out at all in first. Runs strong and shifts hard at correct MPH. Sometimes will not cut out until third gear. It is the not throwing codes that really puzzles me.

 

[dalwine250]

Re: Cuts out under boost

what did you gap the plugs ? it may be blowing the spark out.it could be many many things but sparkplug gap is a starting point.
dave

 

[It's just a six]

Re: Cuts out under boost

You need to describe this cutout. Is it completely cutting off, slower pulling & gradually cuts off,or seems a little weaker?

Might be running out of fuel,bad/weak fuel pump,bad filter?

 

[SY2932]

Re: Cuts out under boost

I didn't see a new fuel pump in your list of mods. As far as you know, is the stock pump still in there? If so it is 15 years old now and may be getting "tired". Monitoring your fuel pressure while you are in boost will tell you for sure if it's not increasing one psi per pound of boost...

Also, don't rule out a chip issue either. Drop the ECM and see if the tape has been cut. When I bought my truck nine years ago, it was overboosting like a mofo. Found out at a syty meet later that I had a non OEM chip in there

.

 

[Quatro]

Re: Cuts out under boost

Plug gap is a snug 35. Plugs are NGK UR6.

Plugs, wires cap, etc and exhaust were all original so I would assume pump is. It does seem like it goes lean. Sometimes will pop & crack and jerk like backfireing . Let off and it will pick up and run smooth as silk. I really don't understand why no codes??

Think I will try pump and a coil next week and see if that fixs it. Also will check for chip. Guess I should order datamaster too. The 92 TY has run strong with no problems for 10 yrs now and I never needed it before.

Mike, are you in Canton? I get there on E LIncoln St about 1 or 2 times a month on business.

Lowell Raison,

Lucasville, OH & Dunnellon, FL

 

[1madgumby]

Re: Cuts out under boost

fuel pump, fuel pump, fuel pump. it is known the you might get to 6 psi. max, then the truck will bariley run for A few seconds until the fuel catchs back up, then it will run fine agin. Change the fuel pump to A 255 liter pump & it will fix it.

Aj.

 

[Ian Turgeon]

Re: Cuts out under boost

My first suspicion would be overboost, then fuel delivery. 10-1 its overboost.

 

[SY2932]

Re: Cuts out under boost

Mike, are you in Canton? I get there on E LIncoln St about 1 or 2 times a month on business.

Lowell Raison,

Lucasville, OH & Dunnellon, FL

I'm not too far far from there, little over and hour NW. I actually bought my truck in Massillion when I was a plant manager down there at my old job. Wow, that seems like that was ages ago.

If the stock pump is in there, upgrade to a Walbro 255 LPH as mentioned by AJ ASAP! You can buy one as well as other syty stuff from Ron Gregory here. A Walbro is one of the very first mods that everyone does since the stock fuel pump is marginal even at stock boost levels. Remember, a new fuel pump is much cheaper than a new engine

...

 

[skipztt]

Re: Cuts out under boost

umm canton...sounds familar..lol

 

[It's just a six]

Re: Cuts out under boost

Any word on the fix?

 

[Six-is-Enough]

Re: Cuts out under boost

My first suspicion would be overboost, then fuel delivery. 10-1 its overboost.

X2.

When it shifts into third the motor is under a lot of load, Which will cause a boost spike. The ECM will see the over boost and cut fuel.

You'll need to extend the wastegate accuator rod on the turbo too lower boost.


BTW a fuel pump is not a bad idea, but will not fix your issue.:2cents:

 

[Quatro]

Re: Cuts out under boost

New 255 pump arrived yesterday. Will install Mon or Tues. Any ideas why it is not setting any code?

 

[Six-is-Enough]

Re: Cuts out under boost

I am not for sure, but I think a over boost does not throw a code. I know when I first got my truck it would overboost in cold weather and there was no code with it.

 

[Quatro]

Re: Cuts out under boost

Got side tracked but new 255 pump is now in and fixed problem. No more cutting out under boost. May have even fixed a couple of problems I didn't know I had. Truck now starts immediately and runs even smoother at idle. Pulls strong in all gears. That said, I think the 92 may be a shade quicker. Guess we will have to put them side by side one day and find out.