S/C Marauder Stumbling need help badly!

dmjarosz said:
Probably not the cause but maybe its the FPDM going bad? Ive seen electronics behave wierdly depending on ambient air pressure, humidity, and temperature.
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It looks like the last place the Fuel Pump gets power through is the Inetia Switch, after the FPDM. So I am thinking that if I measure power there and I have 12 VDC then its not that?

All of you have given me a lot to think about, thanks for all of it!
 
I would also wire the BAP before the FPDM and bypass the hobbs switch once you find the problem.
 
I went up to where my car is and I measure voltage in the wires going into the FPDM.

C3127_Connector.JPG



Fuel_Pump_Circuit.JPG



At the PK/BK wire I have 13.76 volts with the car running.
Does that mean that the problem is with my pump since its getting the full voltage?

Thanks.
 
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Have someone turn the key to the accessory on position while you are down on the ground near the trunk. If your fuel pump is working, you WILL hear it as it pressurizes the system.
 
RacerX said:
Have someone turn the key to the accessory on position while you are down on the ground near the trunk. If your fuel pump is working, you WILL hear it as it pressurizes the system.
Click to expand...

The pump runs, the fuel pressure wont go any higher than 20 PSI at idle.
Im thinking its dying.
 
I put in a new Focus SVT Fuel Pump on Monday. Fuel pressure still reads at 20 PSI when idling, but now jumps to 40 if I rev it up just a little bit. I took the car out for a quick drive and while I didnt get into it really hard, I did get into boost and the problem appears to be fixed. Before I could barely even move the car without it dying.

The bearing in the snout of the Supercharger is going out so thats why I didnt get into it hard and only drove it for a few miles. Now it will sit until I can afford to have the bearing replaced. I shouldnt have these types of problems on a 35K mile car. At the rate things are going the car is going to nickel and dime me to death and I will have to sell it.
 
When your plenum is seeing vacuum, you don't need as much pressure to push the fuel into the heads. When you're under boost, the fuel pressure is more to compensate for the additional pressure. Good news though!
 
This car hates me.


It appears I may have gotten a bad pump, but im not sure and need some suggestions.

I got the supercharger all fixed up and took it out for a drive on Friday night. I’d put about 50 miles on it when I decided to get into the boost. It starts cutting out just like it did before I replaced the pump every time I got into boost. I park it and ponder the situation till Saturday morning when I have to go to work. I get to the freeway and decided to get into the boost. It’s perfect, boosted to the max flying along without a hiccup. Get out of work and by the time I’m almost home its back to cutting out if I give more than a moderate amount of throttle. So bad that I could barely make it up a hill.
Sunday morning I am going to take it to a buddy’s house and have him use his fancy scanner on the car. I hope to limp it there as its pretty close. On the way there again its running perfect, boosted to the max flying along without a hiccup. Get there and he put his scanner on it and no codes, no pending codes. It’s idling while we do this. We go to take it for a drive and it’s like it was Saturday night so we turn around for fear of not making it back. When we do we hook up the fuel pressure gauge and it’s showing 20 PSI at idle and again it’s not increasing the fuel pressure like I think it should. A wide open blip of the throttle has it jump to about 30 PSI and then when the RPM’S drop the fuel pressure drops to near zero before settling at 20 PSI while idling.

I’m thinking I have a bad pump. I checked the voltage at the FPDM before I replaced it and it was 13V+.
Is it just luck of the draw or is something killing my pumps?
This time I also turned the BAP all the way up just to see if that helped, it didn’t.
Why would it run perfect both mornings? Was it because it was cooler, or was the pump just working better and starts to crap out after running for a while?
I’m not thinking it’s any kind of obstruction, or if it is why would it run perfect both mornings.

Is there ANYTHING else I should look at?
 
I don't like your idling fuel pressure, no matter what my info says 35 - 70...at all times. With your fuel pressure jumping all over I would want to know why. What pump did you go with? Your chances of getting a bad pump are slim to none if you used a quality piece. I do not know what you are using for fuel pressure regulation but it seems like its not working properly. Just MHO...
 
I went with a Delphi Pump for a 2003 Focus SVT from Rockauto. The Focus pump is what was in the car when I bought it. I keep thinking the same things, that the odds of a bad pump are slim.

I changed the Fuel Pressure Regulator with another I have on hand.
 
The only other thing I can think of off hand is low fuel, or the tank baffle is broken. Did you notice if the baffle around the pump was still in the tank and mounted?
 
FF1077 said:
I shouldnt have these types of problems on a 35K mile car. At the rate things are going the car is going to nickel and dime me to death and I will have to sell it.
Click to expand...

Hang in there man, I had a few bugs when I bought mine. It had 28000 on it when I picked it up.
I blew the motor 3000 miles after I bought it and found that the original Trilogy install was not so good.
Now 20,000 miles later I'm all smiles, I still work on it all the time but hey, if it wasn't the Marauder it would be something else.

I used the Aeromotive 340 when I dropped my tank.
At WOT I have never seen any more than a 60% duty cycle on it.
My BAP has always been cranked up all the way.

Like Landy said. Buy an Xcal3, download Live Link and go run the car with the laptop hooked up.
You can pick and monitor just about anything, then replay it and watch all the stuff you picked to monitor.

Pretty awesome.
 
If you made sure there is not and obstruture where the fuel travels specially inside the tank. I would not spend another dime untill datalogging it. Also get your self a wideband you wont regret it.
 
Man this sucks!!!! Sorry about your luck.

I have a excal2 that's locked to my car but I believe can be used on any car for data logging. You're more the welcome to use if needed.

I'd be very nervouse about going into boost until you get this figured out. If you've got fuel issues it can still be running lean even when it feels good. You don't want to add a blown motor to your problems.

A wide band and data logging are the only way to know whats going on.

Might want to think about having someone check it out. I would think an experienced tuner on a dyno could nail it down pretty quick
 
FF1077 said:
This car hates me.


It appears I may have gotten a bad pump, but im not sure and need some suggestions.

I got the supercharger all fixed up and took it out for a drive on Friday night. I’d put about 50 miles on it when I decided to get into the boost. It starts cutting out just like it did before I replaced the pump every time I got into boost. I park it and ponder the situation till Saturday morning when I have to go to work. I get to the freeway and decided to get into the boost. It’s perfect, boosted to the max flying along without a hiccup. Get out of work and by the time I’m almost home its back to cutting out if I give more than a moderate amount of throttle. So bad that I could barely make it up a hill.
Sunday morning I am going to take it to a buddy’s house and have him use his fancy scanner on the car. I hope to limp it there as its pretty close. On the way there again its running perfect, boosted to the max flying along without a hiccup. Get there and he put his scanner on it and no codes, no pending codes. It’s idling while we do this. We go to take it for a drive and it’s like it was Saturday night so we turn around for fear of not making it back. When we do we hook up the fuel pressure gauge and it’s showing 20 PSI at idle and again it’s not increasing the fuel pressure like I think it should. A wide open blip of the throttle has it jump to about 30 PSI and then when the RPM’S drop the fuel pressure drops to near zero before settling at 20 PSI while idling.

I’m thinking I have a bad pump. I checked the voltage at the FPDM before I replaced it and it was 13V+.
Is it just luck of the draw or is something killing my pumps?
This time I also turned the BAP all the way up just to see if that helped, it didn’t.
Why would it run perfect both mornings? Was it because it was cooler, or was the pump just working better and starts to crap out after running for a while?
I’m not thinking it’s any kind of obstruction, or if it is why would it run perfect both mornings.

Is there ANYTHING else I should look at?
Click to expand...
I just sent you a pm with my number, i myself want to know and help you fix your problem.
 
Youve both got PM's and many thanks to you both.

As it sits, the car cannot be driven. I have it parked at a freinds place until I can get time to work on it.

Anyone interested in the Torque data log from my cell phone app send me a PM with your email addy and Ill send it to you. Its less than a MB, but to large to post here.
 
Josh and Landy helped me on my car this weekend. Thank you both very much, especially Josh. We got stuck working outside and he was soaking wet.

We got Josh's SCT Tuner hooked up and took the car for a quick drive. At first it started out stumbling just a little bit, but over time it got worse. During all that stumbling it looks like my fuel pump is working within acceptable parameters. Josh and I swapped over his FPDM and regulator to rule those out just in case. It made no difference.


I think it’s safe to rule out the fuel system at this point. That leaves me with air and spark.

When the car is first taken out it doesn’t stumble as badly as it does when it’s been on the road a while. That makes me think it’s not something mechanical, its electrical. I am beginning to wonder if I don’t have a pair of COP’s that have gone bad on me.

I’m even beginning to think stumbling isn’t a good term either. It’s like someone shut the ignition of for a fraction of a second. Josh came up with a good suggestion, to take a video of what the car does when it “stumbles”. It’s going to be a week or two, but next time I am with the car I will do that. Maybe Josh can post his thoughts too.
 
This has had me thinking on your issue. Think of your problem this way. Expandsion and contraction. When things are cold they shrink, when hot expand. So, I wonder if there is air that is getting in not metered. Either through the pipes, fittings or intake itself. Try this, when car is warm and running at temp, get a can of ether or similar, and spray in different suspect areas to see if idle changes etc. What do you think?
 
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