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Surging help

2196 Views 12 Replies 6 Participants Last post by  mthomp1
Surging help -UPDATED with fix!

New truck. Ran good up till a few days ago. It surged a few times, felt like the APPS was failing. Replaced with a Timbo. This morning it did it the worst.

Right off the bat, cold engine, driving down the road, it drops down like you let off the throttle, then comes back. Feels like 1 second increments or so. Did it for 10 miles. Cruse on or off. Floored it still does it. Apps was constant. I got pissed and pulled over, no codes on CTS. Shut engine off, went into gas station, came back, did it for 5 more miles. Got repissed, pulled off road, key on/off codes pulled nothing. Then it ran fine the rest of the way to work.

Think it might be the ignition key, or is it a VP?
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Zero codes when scanned with a Snap On Modis. No codes anywhere. Just drove 20 miles and no symptoms. I'm stumped. You'd think if it was the VP it would be constant?
Truck ran great on the way home, until I came to a stop sign. Engine shut off and won't restart. Didn't see any codes.

I'm soo ready to P-Pump this thing. Is there any VP's that are programmer tolerant? I'm 5 sec away from ripping all the stuff off of it and leaving it bone stock.
Ok, so this is how things went down.

I suspected the APPS three days before it died and changed it... no difference.

After it quit, I took it to a garage where I work. Pulled the fuel line and fuel roared out of the line when the Airdog was on. 12v going to VP44. So we assumed it was a bad VP44.

Get a new VP44 from Progressive Diesel Injection. Put the pump on, starts right up. Go on a little drive and it drives fine. Leave garage, get halfway to shop and it dies. After cranking for exactly 20 sec nonstop, it fires. Drive back to shop ok. On the way home, it dies again. Crank for 20 sec and it starts. Drive a little, dies. Crank 20 seconds, and hear stumbling at idle. Haul butt back to garage and it dies two more times.

We are baffled for two days.

In frustration, we pull the fuel line and I put my finger on the end of it to see how much pressure was there. GUESS WHAT? NADA! Fuel gushed out the first three seconds then it slowed to a trickle. Filters look good inside. Pull fuel tank. Turns out previous owner installed the airdog and 1st - never removed the in tank pump and 2nd - never changed the fuel filters!

In the end I spent $1600 and lots of frustration over clogged fuel filters!

Let this be a lesson. When your truck is doing weird stuff, check your fuel pressure. Actually check it, don't assume! Check PSI and also run the hose into a small bucket and check volume. I wasted a lot of $$$ and time on $40 worth of Napa filters (Which BTW, Napa filters 3626 and 3616 work on the Airdog 100.)
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