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Please help! Truck cutting out on hills.

10705 Views 8 Replies 5 Participants Last post by  Invader1
So I just got home from a fishing trip about 4 hours from home into the foot hills. On the way there, I almost turned around and went back home.

What is happening is at highway speeds, every time I start up any kind of hill, even just a bridge, as I would start any climb, the truck would start cutting out as if it was running out of fuel. If I let up and coast down to about 40 mph, then start to gas it again, it would be OK. Unless I was still going up hill. If I was still climbing it would go OK for a minute or so and then start cutting out again. If I tried to keep an even speed up the hill, it would start dieing.

It seems like it might be having a problem keep the injector oil pressure high enough. When I put the motor under any kind of heavy load, it cuts out. On long flat sections of highway, held at a steady speed, I had no problem.

I thought it might be the MAP sensor so I tried unplugging it and driving a while. Same problem.

Could it be the injector oil pressure regulator? I have a dual HPOP, (Stealth), so I dought it could be the HPOP, but who knows.

Just so you know, I have new fuel filters and a new fuel pump, (Beans fuel system), and I checked the fuel pressure a few times. 60 psi. I also just changed the oil recently so the oil is good.

One other note. Every time this would happen, the speedo would start bouncing a little. So I was wondering about the speed sensor also. Not sure if the speed sensor could make the truck cut out like this and I could not see how the speed sensor could only have problems going up hill but I thought I would mention it.

Any help would be great. I have another trip planned for next weekend so I would like to figure this out soon.

Thanks for any suggestions.
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Almost 45 views and no one has any ideas?

Well I have a bit more info.

I do not like the shotgun approach by throwing parts at a problem but I need this thing running by Friday so I replaced the IPR and the ICP sensor hoping one of them would be the problem.

No change. Still cuts out on hills. And it is not just highway speeds. It does it at any speed. If I try to climb a hill. its cuts out and starts to die unless I let off the throttle and it comes back for a few seconds. If I try to accelerate up a hill it dies out.

Any suggestions please.

If it I had a cracked pick up tube, wouldn't the low pressure oil drop also?
That is one thing I forgot to mention is that the oil gauge in the dash does not drop when it starts cutting out. I check that several times when it was cutting out.

I do have a scanner to check ICP but it was not working until this morning, (my old lap top compurter), and I ran out of time to drive it while scanning before I had to go to work. That will be the next thing I do tomorrow morning is drive the truck while scanning the ICP.

If the ICP is reading low, is there anything else it could be besides the HPOP since I have a brand new IPR and ICP sensor?
Have you tried the CPS? I know it always gets blamed but, I had a similar situation. It would start missing very badly going up the hill pulling the boat and run fine on flat land. Eventually tried the spare CPS and it solved the problem.
Wow. I will give that a try if all else fails today.
So this is weird.

It looks like I fixed the problem. I know what I did, I just don't know how it fixed it.

I talked to my nieces husband who is a mechanic at a Ford dealer in Northern California.

He suggested checking the volume of fuel the fuel pump is pumping to the heads. Even though I knew I had 60 PSI, there might not be enough flow.

So I disconnected the fuel line on the driver side of the regulator to the driver side head, (remember, this is an after market Beens fuel system), and connected a line from the regulator fitting to a 1 quart measuring cup. I jumpered the oil pressure switch that supplies power to the fuel pump and then turned on the key for 15 seconds, I got a little over a pint of fuel in the measuring cup so the fuel volume looks good. At this point I had to get to a doctor appointment so I re-connected the wires to the pressure switch and re-connected the fuel line, and took off to the appointment. After the appointment, I took the truck up a local hill with my scanner hooked up to check the ICP. The problem has not re-occurred. The ICP looked good, close to 3000 psi I at full load/throttle.

To be sure I took a 20 mile drive over a local mountain pass, (about 1700 foot elevation), and back again and the problem is gone.

I have no idea what fixed it but I leave tomorrow for another 4 hour away fishing trip towing the boat. I sure hope this issue does not come back.

Thanks for the help,

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