Intermittent "hiccup" While Driving

[Mattstang04]

Good call Ben830. The shop did some data logging while on the rollers and found that the fuel pressure is falling and then suddenly recovering and then falling again. They are going to test my JMS fuel pump booster to see if it is failing. The thought being that the pressure would not recover if pump was burning out and the spikes in voltage would be more cause by it failing to boost and then recovering suddenly. If this booster is failing, this will be my second JMS fuel pump booster failure. Innocent until proven guilty but my anger is growing.

 

[flstang65]

What fuel pump are you using?

 

[Mattstang04]

I was using the SVT Focus pump. After further examination, the shop determined the voltage is staying constant, the hoses and fuel lines inside the basket and to the tank, fuel filter are free flowing and intact. The JMS is doing its job just fine. Leaving the fuel pump the likely suspect in intermittent dumping of the fuel pressure. I have seen people post that the SVT Focus pump can be a bit fragile and finicky. I have also seen that they don't play well with BAP or any voltage boosters. So by the process of elimination and according to internet speculation (I'm trying not to be pessimistic), a replacement pump is probably the right direction.

The shop is going to put in a Steeda (Walbro) complete unit (with basket). Steeda claims it can support up to 600 hp. Hopefully that means it can support my meager <400 hp. I questioned if it was just a 255 pump but Steeda's site labels it with its own 01 to 04 Mustang part number, separate from the 98 Cobra and the 99 to 00 Mustang. I will assume it's built to sustain the rigors of the returnless fuel system.

 

[flstang65]

Sounds like a step in the right direction.

 

[ben830]

Whoo-hoo I helped!

 

[ben830]

If you can keep an eye out for long tube header for a 99 gt. Thanks!

 

[superstang01]

did you figure this out? my car does this, but only if I'm not revving high and give it full gas

 

[Mattstang04]

I'm waiting for the shop to get her put back together. Not sure if the pump has come in yet but I will let you know if it cured the issue once I get it back. Maybe today or tomorrow depending on the pumps arrival. Are you running the SVT Focus pump as well?

 

[superstang01]

I'm waiting for the shop to get her put back together. Not sure if the pump has come in yet but I will let you know if it cured the issue once I get it back. Maybe today or tomorrow depending on the pumps arrival. Are you running the SVT Focus pump as well?

sure am, I am not too concerned about it though. As soon as my motor goes its getting a coyote swap lol

 

[Mattstang04]

Coyote swap, huh? If you're ready to get that underway, I got an engine additive (bag of sand) to help "fix" that current motor. hahaha.

Still haven't heard back from the shop. Taking their sweet time I guess. If it wasn't for not being able to diag this car on my own, I could have had a new pump in it, in a matter of hours.

 

[Mattstang04]

Update. The pump is in and fuel pressure is restored. Here comes the "but". Now the MAF is pegging. The oil blow by from the valve covers has coated the intake tubing and MAF. Their going to clean out the tubes, intercooler, and MAF. Lastly install a JLT prefilter on the drivers side valve cover then route that vacuum line off the same valve cover to the Moroso oil catch can that I currently have hooked up to the passenger side only. $$$$$$$$$$$$$$$. Dyno time costs soooo much.

 

[superstang01]

updates?

 

[Mattstang04]

Got the car back two days ago. It is running like a champ. Cold starts only takes a couple seconds of cranking as opposed to the several seconds it took before. I haven't gone into boost a whole lot. But I did crank it up once with the AC on and once without. No stumble, hiccup, or hesitation. Pulled nice and hard all the way up to the red line. Got to a full 12 psi of boost.

My faith in the SVT Focus pump is gone. The focus pump didn't last 25xxx miles. I still have the JMS hooked up, we'll see how long this pump lasts. For now, she's alive and kicking.

 

[madspeed]

Good to hear