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Topic: Dead along road... (Read 812 times) previous topic - next topic

Dead along road...

... or actually half in the road.

Background:  At the end of our last trip of 1.5 months, the FT sputtered to a stop about 1/2 mile from our house, after showing no previous symptoms.  I was able to restart it several times and nurse it back to the stall.  I assumed it was a clogged filter - we had the same issue with our previous coach, and a new filter fixed it.  I replaced both fuel filters, primed with the knob on the filter base until it seemed firm, and it started right up and idled well.  I let it run for about fifteen minutes just to be sure.  This was all about a month ago.  Today I started it up pull out of the stall, and I got a half-mile down the road and it does the same thing.  It will start, idle slow and rough, but will not pull at all.

What I know:

When I turn the key, I hear a metallic click on the passenger side of the engine.  (Fuel solenoid?)
The fuel filters were mostly empty and were well-seated.
Tank may have run empty - I usually refill when the tank shows empty, which is actually about 1/3 tank.  Today the tank showed empty, I added about 20 gallons, and it now is about 1/3 by inspection.
When I use the prime button, it never gets firm.
When I use the prime button, I hear air (?) escaping at the engine, somewhere around where the hose from the fuel filter block goes.
I have pumped that prime button a lot.

My thought is that the fuel line where it attaches to the engine is leaking air and I should replace the o-rings in the fuel line fitting where it attaches to the engine (I guess that is the injector pump.)  Or is there a mechanism to vent when the primer handle is operated?  Or does it even work that way - I know that the fuel cycles through the system and does not go only from tank to engine.

Awaiting sage advice.

Matt B

Matt B
1998 u-320

Re: Dead along road...

Reply #1 –
Matt,

Assume you have the Caterpillar manual primer pump on the primary filter. 

If so, and 200 strokes (more than it SHOULD take) does not make the pump go from easy to hard (i.e. air to fuel), then either you have no fuel in the tank, a leak in the hose from tank to primary filter, or a leak at the filter itself.

Also sent you a PM.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Dead along road...

Reply #2 –
Yes, I have the manual primer pump.

So it sounds like all other potential issues aside, if there are no leaks between, the primer pump should draw fuel from the tank, and pumping will become firm when fuel is drawn to that point.

Fuel into draw tube, hose from tank to water separator, water separator assembly, hose to filter, filter assembly, primer, right?

No PM as of 9:56.

Matt B
Matt B
1998 u-320

Re: Dead along road...

Reply #3 –
email rec'd thanx!
Matt B
1998 u-320

Re: Dead along road...

Reply #4 –
As we talked about on the phone:


Fuel into draw tube in tank, hose from tank to primary filter/water separator, hose from primary filter to lift pump, lift pump, hose from lift pump to secondary fuel filter with manual primer pump, hose to engine/injectors.

If there is a leak anywhere BEFORE the lift pump, you would be on the suction side and so air would enter the fuel system.  If leak from lift pump on, it would leak fuel out, as it is on the pressure side of the system.


Same layout as the vast majority of all diesel engines if all makes.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Dead along road...

Reply #5 –
This does not answer your air leak problem, but it brings up a problem with letting fuel tank getting low, other than running out of fuel that is.

Fuel pump recycles a lot of fuel not needed for injectors, back to fuel tank in the fuel return line.

The returning fuel serves to cool fuel heated from injector pump and engine heat.

Cooling of fuel is accomplished by mixing returned fuel with cooler fuel in the tank.

If fuel tank does not have a lot fuel in it, over time the fuel tank heats up and supplies the engine with warm fuel.

Re: Dead along road...

Reply #6 –
Barry, So correct, why some of us add a transmission cooler in the fuel return line.
I try  to get rid of the heat in the engine compartment area, not send it to the fuel tank. There are many little things that all add up for better performance.
Dave M

Re: Dead along road...

Reply #7 –
As Dave did, many years ago I added a Hayden transmission cooler in the return line from engine to tank. 

Particularly if you don't have a fuel cooler,  in hot weather, run on the top half of the tank.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Dead along road...

Reply #8 –
Brett, The first time the issue of hot fuel showed up for me was during a load bank testing of a 3412 Cat Genset, it started loosing hp as the fuel temp went up, so added a Hayden transmission cooler , clamped it on the fan guard, the hp came back up as the fuel cooled down.  Took a while as the 50 gal daytank had to cool down alot.
Crazy how we learn these little things. Not by reading as much as real life experience.
Dave M

Re: Dead along road...

Reply #9 –
Problem solved - I was "out" of fuel!

I must have been really tired when we came home from our trip.  I usually refill when the gauge hits empty, which I have visually verified to be about 1/3 tank.  When we came home, the problem started on a small hill about 1/2 mile from home.  The problem returned at the same spot in the road.

I could see several inches of fuel at the bottom of the tank, but I added about fifteen gallons to rule out a low fuel problem.  Hah!  After talking with my hero Brett, I disconnected the line from the filter to the tank and blew.  Even with the added fifteen gallons, the pick-up tube was still sucking air.  Another five gallons and I was blowing bubbles.  I replaced the hose, pumped the primer and 20 miles with no problems.

Matt B
Matt B
1998 u-320

Re: Dead along road...

Reply #10 –
Matt, et all...Don't feel bad, I ran our 93 out of fuel 3 times. I know,,,,slow learner....problem is, on this coach you have to remove fuel filters, fill with fuel and put them back on..NOT fun when on the side of the road...
We are only strangers until we meet; however, some of us are stranger than others

Re: Dead along road...

Reply #11 –
Glad you got it going.  That is one of the least expensive "fixes". 

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Dead along road...

Reply #12 –
Thanks all!

Lost my wallet for the first time last month.  Ran out of gas and got stopped for the first time today.  When I was 17, I ran out of gas, but coasted into the gas station, so I don't think it counts.

I am surprised I could have so much fuel and still be empty...

Matt B
Matt B
1998 u-320

Re: Dead along road...

Reply #13 –
Yes, The biggie for the VMSpc is the fuel used and fuel on board display, I never look at the fuel gauge on dash anymore as the VMSpc is spot on correct.
Everytime I get nit picky with the VMSpc, it always takes the amount of fuel indicated on the display minus Aqua Hot and Genset, but without either used, the VMXps is correct to the gallon,  I used 106.8 gal, and I could only get 107.1 in the tank, I find that close enough  ;D
Dave M

Re: Dead along road...

Reply #14 –
Quote from: oldmattb –
I am surprised I could have so much fuel and still be empty...

Matt B
Yup. I figure the max range on my 150 gal tank at 800 miles.  That's a conservative 8 mpg and 100 gallons (it's usually a lot less as now I'm getting a consistent 8.6 mpg).  This estimation allows for a minimum 1/3 of the fuel in the tank at all times (50 gallons that are basically unusable).

Peter
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Dead along road...

Reply #15 –
The U240 should easily have the same 800 mile range on a tank, even though it is a 100 gallon tank.

But, there are two issues:

1.  Fuel is used to cool an lubricate the head on all modern diesel engines.  Particularly without a fuel cooler, that doesn't work very well with less than 1/3 tank.

2.  The second is that storing any diesel tank that is not full is an open invitation to condensation forming in the tank and then algae growth at the water/diesel interface.

Even though our coach is for sale, it is stored with completely full fuel.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020