Engine dying problem

[Lindon]

I recently started experiencing a problem wherein while driving along at normal highway speeds the engine starts to die. Sometimes if I release the accelerator and then push the accelerator to the floor board the engine will start to come back to life sometimes momentarily, sometimes the engine actually dies, and sometimes the engine will pickup and run OK. Sometimes the engine continues to run but with almost no power even if the accelerator is pressed to the floor board. The engine may backfire. What I find very puzzling at these times is that by moving the transmission shift lever to neutral I can race the engine with no problem but when I put the shift lever back into the drive position thereby putting the engine under a load again the engine may or may not continue to run. At these times the dash board fuel gauge registers between 1/4 to 1/3 full. While the fuel gauge has never registered completely accurately it does become more accurate as the fuel level gets lower. So there should have been more than an adequate amount of fuel in the tank. The engine fuel pump has only about 6K miles on it. About 1-1/2 years  I added an electric fuel pump located close to the fuel tank. My limited observations are that if I keep enough gasoline in the tank to keep the fuel gauge above the 1/3 mark there is no problem.  All of this makes me wonder if there is possibly a problem with the fuel draw tube which resides inside the 50 gallon fuel tank? Does anyone have knowledge as to what the fuel draw tube is like and whether with age it can deteriorate? Any thoughts about the problem I'm describing?

[Richard Peterson]

So far it sounds like a fuel starvation problem.  Have you changed the inline fuel filter?  Are you sure the electric pump is running?  The engine vacuum fuel pump will pull fuel through the electric pump but at highway speeds will not provide enough flow to keep the carburator full and the symptoms will be such as you describe.  

[phyllaurie]

I'm having similar problems keeping mine running, a new fuel pump didn't matter. My mechanic says I need a new gas tank because mine is probably full of rust. He says that whenever you store an RV with a metal gas tank you must store it full or the empty part of the tank will develop rust which you can't get rid of and he says, "It's like cancer".
Does anyone know of a good source for a replacement plastic gas tank? How about someone in the Santa Cruz area who could install it?

[Horst]

There are replacement steel gas tanks (after market) that you could use. There a few manufacturer's that make them (a google search will turn up these outfits.)
I went to a wrecking yard to find a replacement polyethylene (plastic) 36 gal tank. They were used on certain 70's Dodge vans (1 ton models) and trucks. You'll have to look for a bit at various yards in Moss Landing (PicknPull, etc) and Watsonville.
Last I checked a few years back there was only two or three "new" polyethylene tanks at some Dodge dealers in the mid-west - and they wanted a fortune for them.
You could also look into getting your tank "boiled" out - but it might be beyond that - you won't  know until you drop it and check it out.

[tomfridley]

regarding metal fuel tank rust-
i have heard of a product used in the aircraft industry called a 'sloshing compound'.
after cleaning as much corrosion out of a tank as possible,this compound is poured into the removed fuel tank and 'sloshed' around until inside of the tank is completely coated with this chemical.
the remainder of the solution is removed, and the tank is left to dry inside.
the rust is then in a layered coating that is not affected by gasoline.
if it is good enough for an aircraft, it will do fine in a motorhome.

[Lindon]

Per Richard Peterson's suggestion I did replace the inline fuel filters (I have a second fuel filter just prior to the carburetor). I captured the fuel which spilled out of the fuel filters and fuel line when replacing the fuel filters. There were some black particles, some large and other smaller but notable in the amount. I do not recall having seen this kind of debree on prior replacments. However, the engine dying or running very rough repeated itself when I was relocating the Clipper to a different location in my yard. This makes me think I've either picked up some dirty gasoline or accummulated enough dirt over the years that now the problem is showing up. Of course, as mentioned in another posting I may have accummulated rust at this point. I've been conscious the last few years about filling the fuel tank before putting the unit in barn storage for the winter. I suspect the carburetor may have some dirt particles which made it through the fuel filters and is not clogging up and interferring with the carburetor operation, at least momentarily but then gets flushed out with more fuel entering the carburetor. I'm also wondering if the inside of the rubber fuel filler hose may be deterioriating and flaking off. Has anyone noted such a problem?

[Cookiecruncher]

You might want to try getting some one with high pressure air to blow back thru the fuel line which you removed from the tank side of the fuel pump to unclog the filter that is in the fuel tank (WE call it the sock in the tank) it might be pluged up causing what you are talking about. when you do this remove the gas cap other wise you might blow the tank apart.

You have a Sock type filter in the gas tank a Fuel filter some place along the fuel line and maybe one inside the carb.

[Richard Peterson]

The next thing I would look at is the carburator.  If you are careful, it's not too big a job to dis-assemble and re-build with a kit you buy at any autoparts store.  A book on the type of carb you have is also helpful.  Unless the carb is working properly, the engine will not run very well.  Good luck!  

[Guinnessecco]

I would try trouble shooting the problem some more. Put a fuel pressure gauge in, one of those that also doubles as a vacuum gauge.  I would place it somewhere that you have a rubber fuel hose since that would be the easiest location to insert the gauge.  The best, though would be just before the carburetor.  If you place it before the mechanical fuel pump but after the electric, and you show a negative pressure, then you know there is a plugged line somewhere.  I would suspect that you have dirt in the fuel line, most likely at a fitting that constricts the line a little.  The dirt can jam against the restriction.  I do not think it is the fuel tank unless someone has intentionally poured dirt in there.  In my mind, a fuel tank needs replacement only if there is something structurally wrong with it, like a leak, or a tank the blows up in an accident like the old Ford Pinto’s were prone to do, or the Crown Victoria police cars of more recent years.

[KEYSJUNK]

I have the same problem, which I have been working on for about seven years. I have a 1977 Clipper 21ft, with the 440 engine. I have gone thru almost all of the tricks to find the problem. I've replaced the mechanical fuel pump, installed an electric fuel pump,changed over to a Holley Carb, removed both fuel tanks for inspection and replaced all filters and hoses. I have replaced the ignition coil and checked the fuel tank switch for debris. At this time I have the motor out for a rebuild and I will re-route the fuel line from the mechanicl fuel pump to the carb.  I experence the problem only when the weather is hot. At times I can here the electric pump running as if it is unable to pick up fuel from the tank. I have not gotten into the fuel canister yet to see if it is creating a vacuum in the tanks. From what I understand the gas caps are of the non-vented type. At this point I believe that the fuel tank gets a vacuum and the fuel pumps are unable to pick up fuel. It'en this fun?  Lots of luck with your problem.  PS. I found the same black material in my filters some time ago. The reason I pulled the tanks.

[Guinnessecco]

Sounds like vapor lock. Pour could water on the mechanical pump when it happens again and see if that takes care of it.  Is the electric pump near the tank? If it is, that would take care of the vapor lock.  How about the gas tank switch, could it be letting air into the fuel lines.

[Lindon]

Source of problem turned out to be insufficient electrical charge going to the ignition system at times. In turn, the source for the low electrical charge going to the ignition system was due to the long bolt for the alternator being broken (at cylinder head ... where else!)and a wire to one of the alternator brushes being unattached. The broken bolt had "backed itself out" to the point that the inner alternator belt was riding on top of the bolt but the outer alternator belt was rubbing the bolt head keeping it from completely falling out. I actually discovered this problem quite accidentally after being told by a repair shop that there was an internal problem with the carburetor and I should take it to a carburetor repair shop.

Despite the unattached alternator brush wire and the degraded efficiency of the alternator belts the alternator was able to produce enough charge to keep the unit running most of the time but the battery was losing its excess charge capacity all of which meant a lower electrical charge was being delivered to the ignition system. Apparently at times the amount of electrical charge was too low to keep the engine running normally. After fabricating a "work around" to the broken alternator bolt problem for keeping the alternator securely mounted in the proper position, reattaching the wire to the alternator brush, and replacing the two alternator belts with new ones two things happened: (1) the dashboard ampmeter gauge surged to show the alternator was pumping out a lot of charge (due to chassis battery having  not been adequately recharged for some time) and (2) the engine dying/low power problems stopped completely! I drove the motorhome to work for several days and not once did the engine perform other than fully powered.

As to why I had not noticed I was having a problem with my alternator not putting out enought electrical charge it is because my dashboard ampmeter only moved a very little under normal operations. Thus, I had not noticed when driving that it was not moving at all. Had the ampmeter shown discharge then I would have been quickly drawn to investigate why this was the case. However, the alternator was apparently able to pump out enough electrical charge to keep the ampmeter at neutral even when running with the lights on.

I'm appalled that neither of the two repair shops which looked into the engine dying/low power problem had not picked up on this electrical generation problem while trouble shooting the problem. It was only as a result of having the hood up and noticing the one alternator belt was flipped upside down that I discovered the alternator problem.

A service manager at a third repair shop explained to me it takes a lot of voltage to "fire" the spark plugs properly so the low alternator output resulted in a low electrical charge going to the ignition system.

[Conrad]

Quite a challenge you had.  I have been following the thread. Congratulations on finding it yourself!    

[Richard Peterson]

Isn't that a good feeling to have solved your problem!!!?  When I found my alternator bolt to be broken, I decided to replace it with two bolts instead of one.  This makes more sense to me and I wonder why Chrysler didn't do it in the first place.  Most other engines I've worked on have at least 2 and sometimes 3 mountings on an alternator.  You still need to use the short bushing at the rear of the alternator to fill the space but the front will just bolt right onto the  bracket.  By the way, these 60 amp alternators can be easily converted to 90 amps by any alternator repair facility.  I like the extra capacity, especially when running the refrigerator on 12 volts while driving.