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INKY Newbies · 06-29-2022, 11:56 AM

We have a 2006 Fleetwood Bounder 38N with a Cat C7 300 HP turbodiesel engine that has about 85,000 miles on it including around 23,000 miles we’ve put on it over the past three years since we bought it. The engine performed exceptionally well until last Fall when we started having problems getting the engine to start after it had been setting for more than one day. We have the rig serviced each July and will have it checked out in about 4 weeks if it makes it that long. We’ve been trying to start it every couple of days, but even that long a gap has been harder than in the past. It starts easily within the first 12 – 24 hours (about 2 – 5 seconds). Any longer and problems set in.

After turning the key to the On position for about 30 seconds, I turn it to crank the engine. It starts right up but only runs for about 1-2 seconds before it dies. During that time, it puts out a white/grey exhaust. I wait a short time then repeat the cycle, holding the key in the starting position for up to 20 – 30 seconds. Sometimes, it may take a 3rd try before it starts and stays running. When it does stay running, the exhaust smoke changes from white/grey to black for 3 – 4 seconds before dissipating.

The last few times I’ve started it, the dash info center cycles through three messages: Check Engine, ECU Low Coolant, and Protect Engine. After letting the engine run for bout 15 minutes then shutting it down and restarting, the warning signs no longer appear. I’ve checked the coolant level, and it is at the maximum level.

Has anyone experienced this problem and, if so, what was the cause and fix? We’ll have to drive it about 400 miles with a 2-night layover midway so we’re concerned whether we’ll make it that far. Any feedback is appreciated.

Twomed · 06-29-2022, 01:06 PM

Outside temps??? It sounds like you may not be waiting long enough for the pre heat grid to warm up or it is going bad, low batt amps maybe. White smoke is definitely to much fuel so it is not combusting properly on start. When you cycle the key multiple times it may be overcoming the issue. Try key on...wait 1 minute then start. Do you have a do not start or wait to start or squiggly wire on the dash that comes on in your das lights when you turn the key on?? That is showing you pre-heat is on...need to wait until it goes out when engine is cold, maybe two cycles if below about 40 degrees out.

INKY Newbies · 06-29-2022, 09:06 PM

Outside temps have been anywhere from low sixties to mid-eighties over the past month when we've been trying to start the MH at least every 3rd day, if not more frequently. Trying to avoid disturbing our campground neighbors as much as possible.

After turning the ignition key to the On position, I've been leaving it there for at least 30 seconds before cranking even though the "Wait to Start" message appears then goes out within about 5 seconds. First attempt has the engine starting almost immediately, but then it dies within 1-2 seconds. Happened this morning when temps were in upper 70s. On the second try, I left in the On position for about 30 seconds then cranked for about 20-25 seconds before stopping. I waited about 30 minutes before trying a third time, and it finally started after about 20 seconds. I let it run for about 5-6 minutes, turned it off for a couple of minutes, then tried again and it started immediately. I let it run for about 30 minutes before shutting it down.

I'll start it again tomorrow and probably again on Friday, but the campground will be full over the long weekend so I'll probably leave it setting until Tuesday before trying again.

Skip426 · 06-29-2022, 09:43 PM

Unlike their Cummins counterparts Caterpillar engines don't use an electric lift/primer pump , so waiting after the , wait to start light goes out isn't helpful .

Does your fuel system have a manual priming pump mounted to the fuel filter housing ?

The Cat injection system has a fuel pressure regulator at the rear of the cylinder head above the transmission that should keep fuel pressure in the head when the engine isn't running , your issue sounds like the regulator is leaking fuel back to the tank .

If you have the manual primer , try using it before you attempt to start , if start up is easier then the regulator is suspect.

INKY Newbies · 06-30-2022, 11:59 AM

The engine, and all its components, is located under the MH bed. From reviewing our Cat Operations & Maint. Manual and inspecting the area around the fuel filter from below, it doesn't look like it is equipped with a manual priming pump.

While there is a plug above the fuel filter, removing it and pouring fuel into the filter to prime it would require removing the bedroom floor after disassembling most of the bed. We might have to take that step if it reaches the point where the engine won't start at all.

It sounds like replacing the fuel pressure regulator may be part of the July 25 tune-up process. Thanks for bringing that to our attention, Skip!

Skip426 · 06-30-2022, 12:12 PM

If the regulator is the issue and not an air leak into the system ;I don't believe the engine would be any harder to start after a week or ten days than overnight so , starting daily is just a strain on the starter and batteries .

Here's a photo of the regulator on my 3126B . I'll double check that it's in the same location on the C-7. (Yellow oval )

On my Newmar on Freightliner ; both the pre filter/water separator and final filter with primer pump were relocated to under the battery tray .

EDIT: Online info indicates the fuel pressure regulator is in the same spot on the C-7 as my 3126B

edge68474 · 06-30-2022, 12:24 PM

I'd like to follow this discussion. Thank you.

INKY Newbies · 07-01-2022, 02:53 PM

I’m going to take Skip’s advice and stop starting the MH until we’re about due to hit the road again on 7/22. I will have the mechanic’s shop check things out including the fuel pressure valve. Once done, our report back on our outcome.

wolfe10 · 07-01-2022, 02:57 PM

As Skip has accurately suggested, the two most likely suspects are the pressure regulator/check valve in the back of the head (front of coach) or air getting into the system.

Also, as he suggested do you have the Caterpillar manual primer pump? If so pump it and tell us what you find.

And as with any diesel engine with an intake manifold heater, wait for the "wait" light (if your dash gauges are wired with one) to go out before trying to start.

INKY Newbies · 07-01-2022, 04:20 PM

I’m going to take Skip’s advice and stop starting the MH until we’re about due to hit the road again on 7/22. I will have the mechanic’s shop check things out including the fuel pressure valve. Once done, our report back on our outcome.

wolfe10 · 07-01-2022, 04:24 PM

Really, even if you don't own a single tool, see if you have a Caterpillar manual primer pump.

If you do, pump it until hard and then try to start. Let us know how many strokes it takes to go from easy to hard to pump.

INKY Newbies · 07-01-2022, 04:25 PM

Thanks for the post, wolfe10. I was unable to find the primer pump when viewing from below, and removing the bedroom floor to access from above would be a major challenge with all that would have to be moved. Is there an easy way to access the primer pump I’m missing?

The “Wait to start” light goes out within a second or two. I had been waiting for about 30 seconds before cranking, but last time (yesterday), I took Skip’s advise and started cranking a few seconds after the light went out. Same results as previous efforts. Started on third try after two minute pauses between attempts.

wolfe10 · 07-01-2022, 04:32 PM

If you have a Caterpillar manual primer pump, it will be on the filter head of your fuel filter.

Here is what the manual pump looks like: https://parts.cat.com/en/catcorp/101-1533

If a single fuel filter, look on it. If two fuel filters, check both.

INKY Newbies · 07-01-2022, 07:01 PM

Here’s a picture of the fuel filter that appears to have a rubber boot covering the top. I’ll crawl underneath tomorrow and see if it hides the manual primer pump then will test it out and report back.