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Lynxgolfer · 06-07-2011, 06:30 AM

I wanted to share my experience with those of you who have experienced a loss of power with the Workhorse engine. I bought my coach in 2003, and in 2006 at less than 17,000 miles, the fuel pump went out. Had to remove 55 gallons of gas and drop the tank - the mechanic put a NAPA fuel pump in it instead of the Workhorse part that I had gotten the part number for from Workhorse and provided him. It ran OK for a year or so, but I still noticed it was sluggish and particularly bad on hot days while towing. In 2007, it almost totally lost power and I had to have it towed just north of Birmingham. A Workhorse mechanic kept it for almost two weeks, drove it home several times and couldn't replicate the problem. In the meantime, I put the Workhorse after market vent system on it and replaced the spark plugs and wires (for a second time). It was not throwing any codes. I went to Birmingham and picked it up and it ran fine until I got about three miles from home and it started losing power again.

I parked it for the winter and the next spring, took it to Georgia Commercial Vehicles north of Atlanta. They dropped the fuel tank again, and discovered the NAPA fuel pump and replaced that. Long story short, it kept losing power and I returned it to Georgia Commercial in 2009. They called in a regional Workhorse adviser who outlined the problem from 25 yards away as we were discussing the issue. Seems HR built a small area for engine ventilation in their design and despite adding the vent scoops just behind the grill, the coach was essentially getting vapor lock because the return fuel line was dumping hot gas on top of the fuel pump (thus the premature wear on the original fuel pump). The solution - drop the gas tank, yet a third time, drill a hole in the bottom of the canister that holds the fuel pump that allows hot gas to drain into the rest of the gas tank.

Problem finally solved. I've seen all kind of posts about loss of power and when someone told me vapor lock years ago, I dismissed it. But if you've had the problem of losing power, particularly on hot days and under a load, I'd look hard at the issue of vapor lock. Long, difficult experience and one that is pretty simple to fix if you know what to look for.

tomwalt · 06-07-2011, 06:47 AM

Thank-you for sharing this - well written and good information to have. Was this issue with the 8.1L engine? I recommend you add your RV/Chasssis/engine to your profile. to do this, from the top of this page, go to 'User CP' and then 'Edit Profile'.

**Petro** · 06-07-2011, 07:01 AM

I had a similar problem with my 2003 Chieftain on a W22. When going down a mountain grade in hot weather with the tank at less than 1/2 I would lose power in fact the engine would stop when I hit the bottom of the grade. I would let it sit for 15 minutes and it would start and run fine. Workhorse determined it was fuel vapor lock caused by hot gasoline returning to the tank right by the fuel pick up. They droped the tank and rerouted the return gasoline away from the pump pickup. I never had more problems after that.

DM

Captain Morgan · 06-08-2011, 11:27 AM

Just experienced this problem again on my way from OH to NC last Sunday. Hot day, less than half a tank of fuel, not towing (this time) and lost all power when cresting the top after a long climb. I pulled to the side of the road, shut the ignition off and then restarted the coach. No codes and no problems for the rest of the trip. While on a 6,500 mile tour of the states In 2007 I was plagued with loss of power issues after a long climbs and then backing off the accelerator when heading down the other side of the mountain. I was towing and it was really hot, like 110 degrees plus. Initially I thought I’d picked up some bad fuel in Denver, but after researching others with the same problem, determined it was vapor lock due to the heated fuel return. When the temps are below 85 (guessing here) or I’m travelling on relatively flat roads I have zero issues. Last Sunday was the first time I’ve experienced the issue since that trip in 2007. I talked to my local Workhorse dealer in 2007 and they basically told me it wouldn’t be covered under warranty and most likely was the fuel pump, even though it tested fine. I’m planning to head on another long trip out West and don’t really want to deal with this issue, so I think it’s time to pop a couple of holes in the canister or possibly reroute the return line away from the fuel pump in hopes it will prevent this condition in the future.
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mgscott4 · 06-08-2011, 04:21 PM

Am I correct in assumming that this problem does not apply to those of us that have the dual output fuel filter that returns the fuel to the tank at the filter?

iRV4FUN · 06-08-2011, 06:24 PM

Quote:

Originally Posted by mgscott4

Am I correct in assumming that this problem does not apply to those of us that have the dual output fuel filter that returns the fuel to the tank at the filter?

Don't assume... We need to know more. Please add your RV/Chasssis/engine to your profile. Also, the original post (OP) still needs to provide an RV/Chasssis/engine profile.

Has anyone wrapped/insulated their fuel lines? There has to be more to this than 110F outdoor temperatures?

Last week I discovered (Google Search) that the wife’s Oldsmobile water pump needed to have an Original Manufactured GM water pump because the NAPA water pump didn’t have two holes in the impeller. I had to convince the service manager that her sweet 3.5L GM engine was not “toast”

. To make a long story short, sometimes there is a reason for using OMP’s. But that doesn’t explain the OP problem.

DriVer · 06-08-2011, 09:29 PM

My dealer used direct replacement front hub seals (CR) from a aftermarket parts house (name wit held) and those leaked. Once I got back and the OE Workhorse seals were installed the leaking stopped. I learned this lesson a while back so I will try to use OE parts if I can. My fuel pump was replaced last year (in 2010) using a WCC part.

edgray · 06-09-2011, 06:10 AM

Quote:

Originally Posted by mgscott4

Am I correct in assumming that this problem does not apply to those of us that have the dual output fuel filter that returns the fuel to the tank at the filter?

YES, I think you are OK with that assumption. I UNDERSTAND that the problem of engine heated fuel was ONE of the reasons they went to the "new style" filter. Ed

edgray · 06-09-2011, 06:15 AM

Quote:

Originally Posted by iRV4FUN

Don't assume... We need to know more. Please add your RV/Chasssis/engine to your profile. Also, the original post (OP) still needs to provide an RV/Chasssis/engine profile.......

Back when I served as a moderator I often asked members to add the sig. info, bnut I gave up because "apparently" some members are not comfortable with sharing all that in every post.

OBTW, where is YOURS???

Ed

tomwalt · 06-09-2011, 04:34 PM

Quote:

Originally Posted by edgray

YES, I think you are OK with that assumption. I UNDERSTAND that the problem of engine heated fuel was ONE of the reasons they went to the "new style" filter. Ed

Ed, do you happen to know if this vapor lock was an issue with the WH P32 chasssis with the 454 engine (1999 chasssis year)?

edgray · 06-10-2011, 10:05 AM

tomwalt:
No, I'm sorry, but my knowledge of any such issue on earlier model P-32 chassis is VERY limited. That said, if one of the later model P-32s with the 8.1L, then I would think the fuel systems would be very similar to what is being discussed here, and therefore possibley have the same potential for the problem is causes. Perhaps other P-32 owners can confirm "IF" the problem has affected them.

I may be "off" by a year or two, but I think WCC started using the 8.1L motor in the P-32 chassis in MY2002.

DriVer · 06-10-2011, 10:30 AM

Quote:

Originally Posted by edgray

tomwalt:
No, I'm sorry, but my knowledge of any such issue on earlier model P-32 chassis is VERY limited.

The WCC P32 wide-track production began in 2001 and at that time they were using the 8.1L engine. 2001 to 2003 vehicles used the GF-481 filter. (2 fittings) Fuel systems were changed in model year 2004 and the "Returnless" fuel system (3 fittings) was put into play on all gas model chassis at that time. P32 production ceased by July 2005. That's all I have at the moment.

edgray · 06-10-2011, 10:44 AM

Quote:

Originally Posted by DriVer

The WCC P32 wide-track production began in 2001 and at that time they were using the 8.1L engine. 2001 to 2003 vehicles used the GF-481 filter. (2 fittings) Fuel systems were changed in model year 2004 and the "Returnless" fuel system (3 fittings) was put into play on all gas model chassis at that time. P32 production ceased by July 2005. That's all I have at the moment.

Mike: that info is appreciated, however the question I was not "answering" was about a 1999 P-32. Can you help him?
Ed

DriVer · 06-10-2011, 11:05 AM

For all Workhorse/Chevrolet Chassis dated from 1996 to the year 2000 equipped with the L19 454 (7.4L Vortec) CID engine, the OE fuel filter was a GF-451.

I do not have first hand knowledge if the requirement to implemenment the returnless fuel system was as a result of anything other than the EPA reducion of fuel line vapors in the fuel system. In my expereince, I have not heard that the new system was created to alleviate a vapor lock issue.