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CJBROWN · 04-14-2010, 03:20 PM

Captains log....about 26K miles...

I've had this intermittent shuddering and missing at various engine speeds, mostly when coming off coasting, or after extended idling in traffic, full tank or half, sometimes at full throttle on steep grades. I checked all of my wires (taylors) and cleaned the MAF, have run fuel conditioner, even installed heat shields for the fuel lines over the muffler and cat. Still does it. So....it sure sounds like a dirty pickup-sock on the pump, but since I'm going to have to drop the tank anyway I thought I would just throw a new pump in there for insurance. Coach runs good most of the time, in fact it roars like a lion, but any idling for extended time and it sure seems the fuel pressure has dropped off because getting going again there is a lot of missing, shuddering and surging.

www.rockauto.com has the Spectrum pump referrenced on Oemy's site for $147 plus ship. They also have the Carter one for $347. I'm going to take my chances on the cheaper one.

Yes, I could have taken it in and had it tested, but it's intermittent so surely they would say it's fine. It's such a PITA to do that so I'm time and money ahead just throwing some parts at it. And I was going to buy a fuel pressure test gauge but I figure the $40 or $50 I would spend on one is surely going to tell me I have intermittent or low pressure, so I'm just putting my money on a new pump.

Will post with results on R&R, what I find in there, and whether it cures my issue. Will take pics if requested.

RV Mech Tech · 04-14-2010, 04:25 PM

CJBrown - any chance it could be the fuel pressure regulator? - the pump is in the tank at the back but yourfuel rail, injectors, and fuel pressure regulator are all near the engine and exposed to engine heat - you said that it happens when you are sitting in traffic and thats when the engine heat will increase - I have had a few pressure regulators that have done the same thing when exposed to high heat - I would get a fuel pressure gauge, connect it and go for a drive and have someone watch the gauge under different driving conditions - usually when an electric pump starts to give trble its consistent and stays that way but a pressure regulator can fluctuate - if you drop the gas tank (not a lot of fun on a big vehicle) and change the pump and the problem is still there then you will be at square one- also did youceckthe fuel filter? - when they start getting plugged up ( 60% and more) then the filter can starve the engine and then stop it from running.

CJBROWN · 04-14-2010, 04:30 PM

That's a great idea a definite possibility. My understanding is the regulator, pump, and level sender are all in the pump assembly. Where do I find a pressure regulator on the engine?

The first thing I did when I started having the issue was replace the fuel filter. I have one of OEMY's adapters so I'm using a standard filter. Cut the old one open and it was virtually spotless.

EDIT: in further research my understanding is the on-rail regulator was eliminated in 2004 and the new fuel line configuration and filter took it's place. Perhaps someone can confirm...Oemy, Driver?

billyb · 04-14-2010, 04:48 PM

i had trouble with mine while in alaska, and i decided it was the pump in the tank. rock auto sent me a new one for about 350. when we pulled it out ,it was coated with white powder on the fiber filter on the outside of the canister and also on the filter that is fitted around the actuall pump itself. i bet i could have cleaned them both off and ran fine, but didn't want to chance it at thatstage of the game.

CJBROWN · 04-14-2010, 05:32 PM

Okay, just called Brazel's and they confirmed there is a fuel pressure regulator on the fuel rail, and gave me a part number. Great guys, aren't they?

I'm going to throw one of those on there first.
Local dealer - $126.64
Rock Auto - $78.22 plus $5 to ship, no tax

I'm still at about half of what a repair shop would charge me to fix this thing, and I can do it in my spare time instead of trying to get the coach there, leave it, and pick it up.

Now I have to figure out how to 35 gallons of gas out of the tank.

Maybe we should just do a short road trip and try out the regulator.

RottenRalph · 04-14-2010, 07:02 PM

I don't know if you have one but our local Auto Zone let me use their fuel pressure test kit at no charge.

Oemtech · 04-14-2010, 07:03 PM

Did you check the fuel rail pressure first.. it should be 55-62 psi.

max49 · 04-14-2010, 08:26 PM

I know you said you checked your Taylor wires but your description of shuddering ( good description) and surging sounds like a classic case of a bad plug wire to me. When my plug wire went bad , mine would shudder on acceleration and it felt like I had a thousand gal of liquid sloshing back and forth . Obviously when it was # 5 plug's turn to work it felt like the water sloshed to the back of the rig, then it would pull fair thru the other plugs turns.
When mine did this,I didnt know what it was and someone on this forum. told me I had classic burnt plug syndrome.
I just wanted to throw that out before you dropped the big tank. When my fuel pump started to go bad, it would run fine as long as it had 1/3 or 1/2 tank of cool gas around it.

CJBROWN · 04-15-2010, 12:40 AM

Quote:

Originally Posted by max49

I know you said you checked your Taylor wires but your description of shuddering ( good description) and surging sounds like a classic case of a bad plug wire to me. When my plug wire went bad , mine would shudder on acceleration and it felt like I had a thousand gal of liquid sloshing back and forth . Obviously when it was # 5 plug's turn to work it felt like the water sloshed to the back of the rig, then it would pull fair thru the other plugs turns.
When mine did this,I didnt know what it was and someone on this forum. told me I had classic burnt plug syndrome.
I just wanted to throw that out before you dropped the big tank. When my fuel pump started to go bad, it would run fine as long as it had 1/3 or 1/2 tank of cool gas around it.

Seems like a possibility, but I get clean running 95% of the time. When I first put the wires on one of them didn't clip on properly (I ended up pinching the clip later) and we drove 1200 miles with it hanging off the plug. The darn coach still got over 7mpg running on 7 cyl. But you could hear the miss in the exhaust, and there was a tick in the motor. I was going to take it in for a flat lifter, and then found the wire off on close inspection.
I went over all the wires and they are still like new, they are the red super heavy ones, and they're all clipped on good. Motor is smooth as silk when it's not gurgling. I guess I really need to test the rail pressure. I should have the new pressure regulator in a day or two, will install that first and see how she runs. If it still sputters I'll test pressure and look at dropping the tank to replace the pump.

All good suggestions. Hope to get it ironed out soon. BTW, I'm going to drill some holes in that new pump housing if it comes to that, to prevent super-heating of the fuel. I know that's an issue with these as well. My nieghbor with the same chassis had his shut down in the dez in 115 deg heat climbing the grade out of Laughlin NV. Put him on the side of the road for an hour then it ran fine. His checking revealed the commonly known problem with the return line going into the same bucket as the pump and the lines to the motor going over the muffler and cat.

Gee, for this kind of money one wouldn't think they would have these kinds of issues. I swear, these units have reasonably good components assembled by monkies.

ron55 · 04-15-2010, 06:22 AM

I think you find that most of your fuel problems are ethanol related, the white powder on fuel pump is phase seperation results everbody I know boating using ethanol is having problems and since most M/Hs sit for long perionds as boats I would think it is going to happen. It only takes 6 weeks or .3% of moisture from the atmosphere to cause phase seperation. once it seperates it will not go back and you are left with this white mess.

max49 · 04-15-2010, 07:05 AM

My engine seemed to run fine except on acceleration. When the engine was under load is when it was obvious something was wrong. The easiest way I found to test if I found if it was still missing was to stop the back wheels at the curb, then power over it or attempt to.

DriVer · 04-15-2010, 08:18 AM

Quote:

Originally Posted by max49

My engine seemed to run fine except on acceleration. When the engine was under load is when it was obvious something was wrong..

In my experience what I found with this symptom was a burned out plug wire.

E Tex Engr · 04-15-2010, 09:43 PM

Something similar happened to me this evening. Left East Texas Three days ago and pulled in to an RV park for the evening and left the engine idling. When I came out the engine was missing but still running. As soon as I touched the accelerator the engine died and would not start. I put a fuel gauge on the test connection --It read 15 lbs. I noticed when I would turn the key to the first position, the pressure would rise to 20 and back to 15. I turned the key to first position and back off 5 or 6 times, every time it would rise 10 lbs. When it got to 50 lbs. I hit the starter and it ran OK. I drove it to the RV space with the doghouse off and the gauge in place. 2 hrs. later I tried it again and it seems OK. If the regulator has a return line, It looks like it is part of the fuel rail. This same thing happened to me last year in Tenn. I changed the fuel filter, and it ran fine until now. I did take the filter apart, and it was clean. I am going to try to keep the tank over half full and see if that helps. Were headed to Alaska. We will have time to try something else if it happens again.

CJBROWN · 04-18-2010, 06:35 AM

So, while I'm waiting for my parts I'm still tinkering. Picked up a fuel pressure test gauge at Harbor Freight yesterday. Figured for $20 was handy to have along. It doesn't have the out-flow/bleed-off feature so I can't test flow per minute, but easily connects right to the schraeder valve on the fuel rail.

Fuel pressure jumps right to 60psi when I turn the key, and never moves after starting. Hmmm...starting to doubt it's a failed fuel pump or pressure regulator. Question, is the regulator under that stupid recall clip? If so, I can't believe that's a $100 part, and it's mechanical, so how could it fail from heat? One would think it fail open then, not closed to regulate pressure.

Decided to also try the search for ingition traces in the dark. I thought that was an interesting idea. And even more interesting, I'm getting quite a few on start-up. It looks like at least three wires are arching down through dirt that has coated the connection at the coils. Once it's running none are apparent.

I'm skeptical about failed wires, they are the 8mm super heavy duty Taylors, and they're not that old, maybe 5K miles. I never had any trouble with the stock ones, there is not closed in heat issue on the Sunrise/Voyage models from winnebago.

So, I did get my amsoil PI in, I'm going to put two bottles in the tank with about 35 gallons of fuel and run it. See if I can duplicate the shuddering. When the problem first started 6 months ago I thought it was bad gas so I picked up a bottle of Lucas fuel conditioner. After about 15-20 miles it seemed to have eliminated about 90% of the issue. But it keeps coming back, and there doesnt' seem to be any particular condition, seems totally random, but especially under low-speed accelleration, coming off a coast, or if it idles a long time, or on high-speed like climbing a grade. I think it's just bad gas getting picked up, maybe even some of that water or phase-seperation crap from bad fuel. Maybe the fuel cleaner will fix it.

On a side note, I had one rear outside tire that was starting to get just a few weather cracks. All the other tires are fine, so I thought I would put the spare on, it's practically new. The nuts for the stainless trim rings would not come off, I pretty much ruined the little t-handle tool for them. So went down to the tire shop and they got them off and changed the tire out for me. Question: what do you guys do for a lug wrench in the field? Many times we are not where a tow truck would get to us for hours. Out in the middle of the desert we need to be able to change a tire out ourselves if one got a flat. They torqued the lugs on with one of those giant air impact guns, and I just know I won't be able to budge them with that silly little lug wrench they give us with the coach.