Hey guys,
My 2,000 7.3 with 150K miles have been doing good until the last four weeks. It randomly stalled and once would not start when I got back to it after a 30 minutes lunch break. The stalling happened at unpredictable rpm. Sometimes it stalled at near 2000 while I was still in low gear, other time it stalled when I was cruising on street at 30 miles/hr. Twice it stalled while I was at stop light and at idle speed.

The CPS is new. I replaced the fuel filter and it quit stalling for about 100 miles, I was so happy thinking the problem was fixed but then it stalled again.

Each time it stalled it would take about one minute resting before I could successfully start it again. If I tried to start immediately it simply would not start.

Do you think perhaps it is the two filters in the fuel tank being the culprit? I doubt the filters were ever replaced. I looked around and found a Hutch mod where these two filters were removed. An in-line filter was installed on the frame between the tank and the fuel pump. I just cannot understand why Ford engineers place filters inside the tank, which requires either dropping the tank or removing the truck bed in order to change the darn filters.

Anyway, what do you think is the problem and how to fix it?

Thanks

 

Where in Texas are you?

 

I am in Houston.

 

We have a bunch of guys over there with computers. Need to get your truck on a computer that can read some things like High Pressure Oil (HPO) when this is occurring. Sounds like a high pressure oil issue at higher oil temps. Need to check numbers on the computer to verify.

 

Do you mean the oil was over-temperature and caused the HPO pump to quit working?
If that is the case, how did the over temperature drop so fast to revive the pump?
Since the occurrence is so erratic and unpredictable, how does the computer detect it unless the computer is connected to the engine while driving?

I am just thinking out loud here.

 

Computer reads the HPO pressures from your Injector Control Pressure (ICP) sensor on the driver's side head. The truck, from your description, runs ok when cold. When the oil is cold, it is thicker. When the oil warms up, it gets thinner. This exposes bad o-rings on sensors, Injector Pressure Regulators (IPR) and injectors themselves that otherwise run fine when first started. Your o-rings are OLD. Once that oil gets warm and thin, it finds all the gaps the thicker oil could not flow through, and your high pressure oil bleeds off and shuts down the truck. Once the truck cools enough, it will restart. If the o-rings are still original, you are due for preventive maintenance on ALL OF THEM in your oil and fuel systems. The o-ring material used back in 2000 is FAR inferior to what we have available today.

I am not ruling out your pickup foot and screen filters in the tank, but without a computer to see the HPO pressures you can't rule out HPO leaks on warm/hot oil. Those are very common on these engines at this age if still running original o-rings in the oil and fuel system.

 

You MIGHT need this: Combo Kit - 1999-2003 Ford 7.3L

but, if you are still running original o-rings you certainly need it.

 

Mike, thanks for the explanation.

There is only one thing that I do not understand. The truck would start up again within less than a minute after it stalled. Does oil cool down and thicken that fast? Sometimes it could not start in the morning while its engine was cold. Let it sit for about five minutes after several unsuccessful cranks and it fired right up after first crank. It was really weird.

How long does O-ring usually last? my truck has 150K miles. My next door neighbor has same 7.3 with 240K miles and he has no problem with O-ring. It is amazing how his last that long with nothing much more than routine maintenance on normal wear and tear.

How much should I expect to pay for replacing these O-rings?

 

If you replace them all, like I did one fine weekend, it will cost you around $150 for every o-ring on the top of the engine (fuel and oil). They get very soft and mushy over time (17 years in your case), and they fail. Check your truck for trouble codes stored. You should have some since it is shutting down on you while driving.

Without a computer that can see information your truck computer can see, it is all internet sleuthing on my end from past experience and the experience of others. You could also have a bad/dirty/loose IPR valve (very common with old o-rings), some loose valve cover gasket connectors (common), a compromised 42 pin plug over the driver's side valve cover, broken pickup foot in the fuel tank (common), clogged screens in the fuel tank (common), etc. You need diagnostic numbers (oil pressure/fuel pressure/fuel inj. pulse width, etc) to continue without resorting to a guessing game. If I were there with your truck, it wouldn't be a guessing game...I have the computer and tools to figure it out...but, alas, I am not there (wish I was, though).

 

Mike,
Thanks so much for the information. I'll take it to the shop and see what data they collect on their computer. I'll check back with you for consultation again.

Did you do all this on your truck as a hobby?

 

How old is the oil, what weight, and is it to the full mark??

What color is your new CPS?

Was it raining or damp when the failures develop?

Denny

 

Sounds to me like you may have a or some wires shorting out.

 

Denny,
The oil is 3,000 miles old, standard 15-40 non-synthetic Delo and it is almost to full mark. How does the oil age, volume affect the stalling?

The CPS is grey color and was bought at Autozone.

No, there were no rain at all when it stalled.

Tommy,
I thought about electrical shorting and checked all battery cables. They are all tight and batteries are three months old. Both read 13V.
If there is a short it should not re-start at all, right?

 

Tommy,
I thought about electrical shorting and checked all battery cables. They are all tight and batteries are three months old. Both read 13V.
If there is a short it should not re-start at all, right?[/QUOTE]

"Wiring harness", vibration, not necessarily battery cables. Then again, best advice is to get hooked up to a scanner and read codes. We could guess all day, codes could narrow the process.

 

The oil level is important to fire injectors.

The CPS should be OEM only as there are related problems to knock off or aftermarket units causing the same symptoms. If you don't have a spare, get an oem and take the few minutes to rule that out and throw your used one in the glove box.

The socks in the fuel pickup will show symptoms such as: The truck will begin to run rough and diesel (knock) and shake before it shuts down completely. I had this happen to me. It generally won't just stall right out. It will gradually lose power.

A quick check is called the "wiggle" test to determine a wiring issue.
Start the truck, be mindful of the fan and belt and don't wear any lose clothing (IE: a hoody with the draw strings dangling) Start in the engine bay and systematically wiggle each wire. Pay close attention to what you wiggled. I use painters tape and just flag up the harness to make sure I don't miss one. There will be a large connection that is clipped to the drivers side valve cover. This is the infamous 42 pin connection that has a reputation of chafing thru and grounding out.

I have a chip in my truck and when reinstalling the PCM I inadvertently did not torque the 10 mm bolt thru the firewall. My PCM would lose connection briefly and shut the truck down when I wiggled it.

After you make your way thru the engine bay doing the wiggle test, move to the cab and start there. Most of the connections that would be affected are at knee level under the cluster.

If you lose power while doing the wiggle test. You found the problem. It's free, cheap, and it's what any mechanic will do to eliminate that issue.

Scanning the truck for codes as mentioned should put you in touch with other causes, but you can try these steps to help narrow the search before paying.

Good luck and keep us posted. BTW is your truck chipped and do you have more than a 1/4 tank of fuel??

Denny