Need your thoughts after dyno results

[flamedstang95]

Took the car in for a tune last week, got it all strapped down then realized my intercooler pump was bad so we had to stop for the day. Ordered a new pump from Steve@Tousley for 97.50 shipped to my door. Installed the new pump and went back for a tune yesterday. Car made 470/483 but my tuner said he is going to bring the timing down to 18*(from 19) the next time I go in so I won't be expecting those numbers during the next visit.

Problem I'm having is that my fuel pumps are at 45% duty cycle at idle, my tuner said they should be at 35%. Is this a sign of weak pumps or a possible FPDM? I would think stock Cobra pumps would support 470hp, I could be wrong though. I'm new to '03 Cobra's(been a 5.0 guy for 13 yrs) Any advice you can give would be great. I can't afford Lethal's return style set up with Fore hat at this time. I do know that it'll be recommended in the future with a KB but that is a few years away.

Car has 80k miles on it and the fuel filter was the dirtiest I've ever seen. Just bought the car 2 weeks ago today

Thank you

 

[MoKo_03SVT]

im no expert but, im pretty sure as long as they arent maxed out then, there isnt much to worry about (and they are only at 45%). especially at idle. iseems like you should be more worried what they are at while at WOT, with rpms close to redline. with a 2.8 upper, JLT RAI, steeda cat-back, and BAMA tune, mine were real close to maxed from around 5.5k rpms up.

 

[NateTermi]

45% is actually 90% because there are 2 pumps. I think that's right. Just add a BAP if it'll make you feel better.

 

[01yellercobra]

45% duty cycle at idle is bad. You should be closer to 20%. Stock Cobra pumps should be able to handle that power level, but if the filter was never changed then there's a chance one of the pumps is fried. Unforetunately the only way to check is to drop the tank and power them up.

And twin pumps doesn't mean that you automatically multiply the duty cycle by 2. It depends on the PID used. For my set up with twin GT pumps I was up to 95% duty cycle. If you doubled that you're at 190%. Which isn't possible.

 

[flamedstang95]

45% duty cycle at idle is bad. You should be closer to 20%. Stock Cobra pumps should be able to handle that power level, but if the filter was never changed then there's a chance one of the pumps is fried. Unforetunately the only way to check is to drop the tank and power them up.

And twin pumps doesn't mean that you automatically multiply the duty cycle by 2. It depends on the PID used. For my set up with twin GT pumps I was up to 95% duty cycle. If you doubled that you're at 190%. Which isn't possible.

Yes that is what my tuner said, 45% is way too high at idle. Like I said, when we changed the fuel filter it was just awful...almost dirt like. I've been reading and reading on this topic and I've narrowed it down to 3 things(IMO) 1 of the pumps is bad so the other is having to work harder, a possible FRPS on it's way out, or I need a BAP. Given the fact that the fuel filter was so bad I agree with you slo, I think one of the pumps is bad. Now if I swap both pumps and the problem persists what direction should I go? BAP? Could it be a possible bad FPDM? Thank you very much

 

[01yellercobra]

The FRPS would cause bad driveability. I'm 99.9% sure it's one of the pumps. I'd swap in GT pumps with the wire upgrade since you're there.

 

[flamedstang95]

Car drives great, doesn't buck or anything. Can't take it over 4200 rpms though, that's when my fpdc is at 100%

 

[Quagmire]

something is clogged. drop tank and figure it out.

 

[04sleeper]

Sounds to me like a ruptured line in your tank or a weak pump.

Either way you will have to drop the tank and find the issue.

 

[2002BLGT]

GP 1000HP Mustang Sleeper Tank Fuel System (1998-2004) Glenn's Performance

 

[Bdubbs]

I really get a kick out of many people saying "you shouldn't need a bap at that hp level". Many people (including myself) have maxed out there fpdc with just an upper pulley swap. Mine was at 100.7% making 455/479. With a bap and wiring upgrade added, I'm now around 31-33% while cruising and 85% at wot. This reading is off my aeroforce gauge, so you do NOT multiply that by 2! On handheld tuners you have to multiply the number by 2.

Unless I have a pump going out? But the car drives just fine now.

 

[01yellercobra]

Sounds to me like a ruptured line in your tank or a weak pump.

Either way you will have to drop the tank and find the issue.

A rubtured line would cause a no start issue. All the fuel would be going straight back into the tank.

I really get a kick out of many people saying "you shouldn't need a bap at that hp level". Many people (including myself) have maxed out there fpdc with just an upper pulley swap. Mine was at 100.7% making 455/479. With a bap and wiring upgrade added, I'm now around 31-33% while cruising and 85% at wot. This reading is off my aeroforce gauge, so you do NOT multiply that by 2! On handheld tuners you have to multiply the number by 2.

Unless I have a pump going out? But the car drives just fine now.

Some people need a BAP, other's don't. I had a fuel system that should have been able to handle 500rwhp, but it maxed out at 450.

You don't have multiply time 2 with hand helds. It depend on the PID that is chosen when datalogging. My datalog set up goesn't all the way to 100%.

 

[flamedstang95]

Hoping to get new pumps dropped in tomorrow and go from there. I plan on using the stock fuel line on the pumps because my tuner told me that new fuel hoses deteriorate when submerged in fuel(don't know how true that is) Should I do a PPRV delete while I'm in there? What does that entail? What clamps do you recommend when installing the lines to the new pumps? Sorry for all the questions, this is all still very new to me.

Thank you

 

[01yellercobra]

They have a submersible line, but it's not cheap. To do the PPRV delete you need a Y connector, some submersible hose, and clamps. I did it as a preventative measure way back when. But it seems the shift hesitation that the PPRV is known to cause can be tuned out. I can't remember the name of the clamps I used, but they have a normal screw through them and actually crush when tightened. So if the screw backs out the clamp stays tight.

 

[flamedstang95]

What should my fuel pump voltage be? I can data log that too with LiveLinks

 

[Bdubbs]

A rubtured line would cause a no start issue. All the fuel would be going straight back into the tank.





Some people need a BAP, other's don't. I had a fuel system that should have been able to handle 500rwhp, but it maxed out at 450.

You don't have multiply time 2 with hand helds. It depend on the PID that is chosen when datalogging. My datalog set up goesn't all the way to 100%.

Interesting, I've yet to see someone with a predator handheld not have to multiply there FP by 2.:??: Mine only goes to 49.99% Where do I change that?

 

[04sleeper]

A rubtured line would cause a no start issue. All the fuel would be going straight back into the tank.

No. You are wrong.

I have seen lines with small holes and leaking "Some" fuel back into the tank and the car still run fine. You just see the duty cycle go up. I have seen it many times.

 

[01yellercobra]

Interesting, I've yet to see someone with a predator handheld not have to multiply there FP by 2.:??: Mine only goes to 49.99% Where do I change that?

There's the difference. I use SCT. I've never used Predator stuff.

No. You are wrong.

I have seen lines with small holes and leaking "Some" fuel back into the tank and the car still run fine. You just see the duty cycle go up. I have seen it many times.

I see what you're saying. When you say ruptured I'm thinking of a hose that has a big hole blown in it. I don't consider a small hole as ruptured. So I don't think I'm wrong.

 

[flamedstang95]

Just as a shot in the dark I changed the FPDM and the FPDC dropped to 42% from 45%. That's still too high though, FPDC is still maxing out at 4200 rpms. Dropping the car off with my tuner tomorrow to have him swap the pumps. I'll report my results...thanks for all of the feedback.

 

[flamedstang95]

Got the car back this afternoon after getting new to me used pumps put in. Supposedly there were 17k miles on these pumps, IDK. My fuel pumps aren't maxing on now until 5700 rpms. So ultimately I need a fuel system soon, but I already knew that.

Thanks for all of your help