Hard Starting Plus

[Hammerdown]

We are new to the RV'ing world, purchased our R-Vision 27 foot MH in March. It's a 2002 8.1L 4-speed with 43K miles. We're in MI and bought the MH in New York, drove it home without incident. There was a recall on the refrigerator that had not been completed by the previous owner. In driving over to General RV for the recall it totally quit. The ignition switch fried. After getting it repaired I added the relay by-passes as recommended by Workhorse. We made our maiden voyage in June. The morning we were leaving it took about twenty tries to get it to start. We covered about 1600 miles with no further problems. When we returned home I changed the fuel filter. It has only been driven about 50 miles since the filter change when it was put back in storage.

We are now preparing for a trip out to AZ. After taking it out of storage it again would not start, another twenty or so tries. Let it sit for 60 minutes and it started on the first try. On another short local trip it quit while running 35mph, pulled off the side of the road and it re-started on about the sixth try, quit again about 1000 feet down the road and started right away. Returned home where it sat for 30 minutes, went to start it to pull it in the backyard and it took fifteen tries before starting. It quit again after getting it parked, ran for 5 minutes at the most. I pulled the engine cover, checked all the wiring, found nothing, put my OBD II code checker on it and it showed no codes. It then ran idling for 10 minutes before I turned it off.

Any ideas on what to look at?

Dick

[motohomer]

Hammerdown, we just had our fuel pump replaced which fixed our problem but our symptems were not identical to yours; ours was hard to start only when hot but never died while running. The workhorse facility was able to do a quick diagnostic to determine it was the fuel pump. Our scan gauge did not throw any codes for us either in this situation. Hope this helps, good luck!

[Hammerdown]

Thanks for the reply motohomer. The fuel pump was my thought as well but I was hoping it might be something else, the gas tank is almost full!

Dick

[RottenRalph]

Fuel pump would be my first thought as well but the cold starting issue doesn't fit the profile. (at least not when my pump went bad). Could also be the fuel pressure regulator. I borrowed a fuel pump pressure guage from Auto Zone to determine my pump was not putting out enough pressure.

Good luck
Scott

["007"]

I would check your ground cables from battery to frame and a braided one between frame and engine make sure they are tight not loose and dirty. May use a star washer if need reconnection.

Welcome to irv2 and the RV world and enjoy the forums.

[motohomer]

Our pump problem turned out to be the internal pressure regulator. When the pump turned off, the pressure would bleed down immediately. This in turn led to vapor lock on hot restarts.

As Scott said, check the pressure (its easy).

But from the sounds of it, I think 007 is right with it being an electrical issue.

[Hammerdown]

First, thanks for your suggestions.

Here's the latest. I bought a fuel pressure gauge, attached it to the fuel rail. It started on the first try, pressure showing 48# while running. Turned it off, it restarted on first try. I let it run for a couple of minutes, turned it off and let it sit for 30 minutes. Checked the fuel pressure, it was now showing 52#. Tried to start it, fuel pump came on, pressure jumped to 56#, it did not start. Pressure back to 48#, tried to start it 10 more times, no start, pressure holding at 48#. Seems like fuel pump only comes on during first start attempt, that is when the fuel pressure jumps to 56#. Removed the vacuum line from the fuel pressure regulator, clean and dry. The fuel filter has about 100 miles on it.

I let it sit for 15 minutes, sitting pressure grows to 52#, first try fuel pressure jumps to 56#, no start, repeated tries, fuel pressure stays at 48#, no start.

Never fails to turn over, just won't start. Battery connections good, engine ground strap good.

[RottenRalph]

In my case, I had 49 - 51 lbs no matter what I did. After I change the pump, it would have 65 Lbs for 1 second then I would here a click (maybe the regulator) and the pressure would go straight down to 50 Lbs.

Hope this helps.

[Full-Timers]

I would say it's not the fuel pump. The engine should start with no problem at around 55psi. You stated "Tried to start it, fuel pump came on, pressure jumped to 56#, it did not start." It had plenty of fuel pressure to start.

[Hammerdown]

I'm starting to lean toward a problem with the PCM. I have found used ones from a Chevy Suburban 8.1L 2004. My MH is a 2002, do you think it will work?

I have also read of crankshaft sensor failures, is that common?

Dick

[DAN L]

Quote:

Originally Posted by Hammerdown I'm starting to lean toward a problem with the PCM. I have found used ones from a Chevy Suburban 8.1L 2004. My MH is a 2002, do you think it will work? I have also read of crankshaft sensor failures, is that common? Dick

a bad crankshaft sensor should show an obd2 code. they are not expensive and are easy to replace. use the same spacers from the old one on the new one.
if you replace the sensor, you may get a pending code and have to go through a "learning procedure." my engine runs fine without doing this procedure but i get a "pending" obd2 code.
the process for accomplishing the learning procedure is in the workhorse manual.

[Hammerdown]

Thanks Dan,

I don't show any codes so maybe I can cross that one off my list.

Dick

[Hammerdown]

Today's update.

It started on the third crank today, turned the key, fuel pressure at 56#. It idled for five minutes at 48# and quit, pressure stayed at 48#. Restarted on first crank, ran for 10 seconds and quit again, pressure still at 48#, still no codes. Would not start again in 10 tries.

Dick

[mfire1339]

Sounds like you're back to the ignition switch and related connectors. For kicks try tipping steering wheel to different position.

Mike