New here. My truck is fuel starved again!

[rickv100]

I am going to resurrect this thread. I just had the same thing happen yesterday. Truck has been running great, just drove it about 20 miles each way the day before. Yesterday could not get out of town before the truck started acting like it was a fuel starvation issue. I replaced the fuel pump last year and I cleaned the filters out on the side of the road. Truck won't go about 20 feet and then I loose power.

I have the Ducieller distributor. I had just bought fuel at the local gas station so I am thinking either bad fuel or clogged fuel line.

The sediment bowl is filling with no problems, the issue seems to be forward of the fuel pump.

Rick

[hieronymusbotch]

Update:

It's been awhile, a lot has happened, and a lot has been done. all apparently to no avail as far as the original issue goes.

All your feedback guided my efforts and is much appreciated. Once I had gone through the fuel system to my satisfaction I switched my focus to the ignition system and found it wanting. I was getting almost no spark from the coil.

Rather than spend time trying to suss out what the specific issue was, I did what I had been hoping to do for some time and replaced the whole system with a Pertronix electronic ignition system. I purchased their drop in distributor setup and a a 40,000 volt 3amp coil. Bought new plugs and set them to the wider, recommended gap. I even sprung for a new set of plug wires from Magnecor.

The end result was fricken amazing. All of a sudden the beast had some real power. I could drive up most hills without gearing down. Acceleration was noticeably improved and overall the driving was more powerful and smooth.

Then it did it again. Same behavior as the previous three times. Driving down the interstate when she starts to sputter. Pulled off at the next exit. Popped the hood. It's idling great and I can find nothing out of the ordinary in the engine compartment. Start off again and she dies almost immediately. Starts up as soon as the tow truck arrives but I have it towed to the garage anyway. My mechanic can find nothing wrong. He keeps it for a whole week and drives it everywhere. It never repeats the behavior. I take the truck back, go through everything again. It is still running better than it has a right to. Does so for two more weeks then dies again, on the highway, same bad behavior.

I am utterly flummoxed. Lets review.

I have replaced the following items with brand new parts:
Fuel pump
Fuel lines
Fuel filter
Carburetor
Distributor
Coil
Spark plugs
Plug wires

Each time what I do seems to fix the problem and fills me with pride, only to have that pride crushed when it does the same thing in a couple of weeks.

I am preparing to hunt for vacuum leaks and check all the electrical ground connections and wires generally. Planning on giving the new carburetor a good going over since I think I mucked up the mixture screw seat the other day in a fit of frustration. When I put it back in I will take special care with the install in hopes that the problem is in the carb and block attachment.

Again, the problem seems heat related since the engine has been running hard on hot days each time it happens. It acts fuel starved. It usually starts back up in an hour or so but seems to be awhile before it runs proper again.

Interested to hear what you come up with, Rick. Thanks again to everyone for your input. Anyone who lives in the RI area and wants to give a look see, contact me.

Wayne


Three

[SafeAirOne]

Can you get around the problem immediately by jumping a wire directly from the battery positive to the coil positive (bypassing the ignition switch) and starting it up? CAUTION: If it doesn't start, disconnect the jumper--Supplying power to the coil for any length of time with the engine NOT running will fry the Petronics ignition.

When the problem happens and you disconnect the fuel hose at the fuel pump inlet, is there a 'wooshing' sound suggesting a vacuum has built up in the fuel supply line? If you re-connect the fuel line, does it start up after a few cranks?

Have you examined the inside of the air intake hose to the carb for delamination/intermittent blockage?

[ignotus]

Hi, What you are describing sounds a bit like vapor lock. If your fuel line runns directly atop the engine it may be getting overheated causing a vapor bubble at the highest/heated point. IIRC on petrol motors the fuel line ran between the valve cover and the radiator top hose from the factory. It has been awhile since I've had a petrol Rover. Anywho just a guess/option.

gene

[parrie]

Considering that you have replaced about every logical part I would agree agree w/ ignotus...sounds like it possibly could be vapor lock. Has the original fuel line routing been altered? Check the fuel line routing to see if it may be too close to the engine or possibly exhaust manifold. Vapor lock would definately explain the ghost-like symptoms.

[thixon]

If you'd like to test the vapor lock theory, try installing an electric fuel pump.

Just install it in-line with the mechanical pump, and as close to the fuel tank as possible. They're designed to push the fuel instead of pulling it. Also If you install it under the hood it can/will act as a heat sink of sorts and actually cause vapor lock.

Are you running fuel with ethanol? If so, that will increase your chances of vapor lock.

[SafeAirOne]

Hmm. It would be VERY odd for vapor lock to occur while you are driving at highway speeds unless the fuel line is running around the exhaust manifold for a few turns. At those revs, there should be plenty of cool fuel from the tank being run continuously through the line to the carb so that it will not boil off (vaporize) and cause vapor lock. Vapor lock normally occurs after you shut down the engine, allowing the fuel parked in the hot spot in the line to heat up to the point where it changes form.

Stranger things have happened, I suppose...


Note that this is usually the spot where a half dozen people chime in, citing examples of times when vapor lock happened to them under the same circumstances, proving my theory wrong...

[hieronymusbotch]

I have been mulling over the vapor lock possibility for awhile now. It does seem strange that it would occur while driving on the freeway, as I've only ever experienced it (in other vehicles) after sitting hot. I have been running the truck hard in very hot weather, and running ethanol rich fuel... so perhaps... I guess.

The fuel line runs in the stock location, between the valve cover and the radiator top hose, and has not had an issue in five years with that setup. Can't put my finger on anything different in the engine bay to have caused a shift in behavior (aside from the crazy theory that just popped into my head that my having painted the chassis silver as opposed to the original black has caused the heat from the exhaust to be reflected back into the engine bay instead of being absorbed and pulled away... crazy, I know) Generally, because it has been running so well of late, I have been running the truck harder, in the heat, in the city and on the freeway for 45min trips each way.

I am running a weber 34ICH carb with a K&N oil gauze filter (fairly well maintained) mounted directly on top. This was the setup I inherited a decade ago, no issues.

Found no evidence of vaccum leaks anywhere.

I have had the electric fuel pump suggested to me before, but have been reluctant to add another electric element to the system. Feel free to try and convince me. Perhaps suggesting part numbers to check out.

Suggestions on cooling down the engine compartment, particularly on the manifold side would be welcome. This problem has definitely been heat related and the climate does not look like it's cooling down anytime soon.

A difference from my stock setup has just occurred to me... The fuel line running from the tank to the pump (rear tank, mechanical pump) Was originally the hard plastic tubing. I replaced it with soft rubber tubing. Diameter is correct. Seems to flow well. Couldn't find a source for the original. Any thoughts?

[parrie]

I agree, not the normal circumstances for vapor lock but not out of the question. I would not be surprised if ethanol was playing some role in this...from what I understand ethanol actually promotes the collection of moisture (water through condensation) in the fuel tank. I know for a fact that untreated ethanol fuel in a 2-stroke engine can be fatal for this reason. I use ethanol fuel treatment in most all of my vehichles, ATV's, lawn mower, boat motor, etc. especially if they are going to sit for more than a couple of weeks.
Is there any chance you could have accumulated moisture in your fuel tank?

I'm not a big fan of adding electric fuel pumps either but hooking one up in-line to test verify fuel flow is a pretty good idea and should give some quick feed-back. Before you hook one up check the oulet pressure of the pump being used, some electric pumps are putting out some serious pressure.

[SafeAirOne]

What does the inside of your fuel tank look like? How about the screen on the bottom of the draw tube in the tank?

I mentioned this quite a while ago, but your description of the recurring problem still sounds like a classic case of a fuel defecit, where the in-tank fuel pickup screen gets clogged up with the very fine particles of junk floating around in the bottom of your tank and only lets so much fuel by, enough to get you around town and a distance down the highway till the high revs require more fuel than will fit through the clogged pickup screen.

Eventually the engine will start to sputter and die and initially you can still get it to run at low RPMs but soon enough of a suction will develop in the lines that the engine won't even idle. When you let it sit for a while with the engine off, the suction in the fuel lines (from the fuel pump trying to suck fuel from the tank) eventually equalizes by drawing whatever fuel will fit through the clogged screen and the engine will start and run normally until that fuel defecit builds up enough to affect the engine again.

Imagine a McDonald's straw blocked off on the bottom except for a pinhole opening. You can't draw enough soda through the straw to quench your thirst, but if you leave the suction there, eventually the straw will fill with soda. Same effect here.


Even though you may have cleaned the tank and screen a while back, if you don't address the source of the junk clogging the pickup screen, it will keep happening.

I think this is a more likely scenario than vapor lock, personally.

The way to verify that it's a fuel supply problem is to introduce an alternate fuel source when you are experiencing the problem and see if it starts. Simplified: Carry a can of starting fluid and squirt a small amount into the carb and see if the engine will start briefly. If it does, your problem is fuel supply-related. If not, it's ignition-related.

If it were me, I'd quit calling the tow truck if I was able to get it to run again by letting it sit for the amount of time it takes for the tow truck to show up. Those tow trucks can get expensive after a while and AAA only gives you so many tows per year...

[hieronymusbotch]

The issue of moisture in the fuel due to ethanol in the fuel is not impossible, but I have been refueling every week lately what with all my driving.

Will need more information and research on the appropriate electric pump before deciding.

Here's the skinny on the fuel tank: Military rear tank. Had a very slight leak prior to my frame up rebuild. Thoroughly cleaned and resurfaced the tank interior with the Por15 fuel tank kit. Very pleased with the results. Beautiful surface with no signs of lifting and no leaks atall. The sender unit is new. The unit developed an issue when the filter screen loosened and would get sucked up to seal the end of the tube. Serious design flaw. This was easily remedied by grinding the tube end at a 45 degree angle. Have checked the tank and screen more times than I can count since and have never found an issue. Clean as a whistle.

@Mark- Agreed on the towing.

[SafeAirOne]

You're not making this easy!

Well, next time it does it, I'd try the starting fluid trick to see if it's a fuel issue or not, then quickly try to bypass the ignition switch by going directly from the battery + to the coil + and trying to start it as detailed in my earlier post. That will eliminate (or confirm) 2 possibilities right there and you can chip away at the problem.

I forget, is this a Series III?

[parrie]

Perplexing predicament. I agree w/ safeair one, your going to have to try one of the methods mentioned to confirm one way or another if it is a fuel issue or spark...maybe pack a lunch and take a ride this weekend until the sympton arrises and be prepared to try the starting fuid and bypass the ignition.

I went back to the beginning of the thread and read back through...the one item that keeps coming up is running it hard, in the heat, on the highway. I'm guessing that the truck is going for all it's worth while your on the highway? How long a trip are you making at break-neck speed? Have you noticed what the water temperature is when driving down the highway? Where the fuel line passes over the radiator gets very little, if any, air flow. It seems that this could be another possible hot spot if conditions where right (high ambient temp, high water temp, low air flow, high speed).The vapor-lock theory may be far-fetched but in the words of Mr. Spock...it's a logical explanation. Do the symptoms only occur when the ambient temperature is hot and at high speed? Maybe she just can't be pushed that hard for long distances in the high heat.

[ignotus]

Here is a link to the topic that might be useful from the Series 2 Club Forum in the UK.

http://www.series2club.info/forum/index.php/topic,56628.0.html

If you can't access let me know, or join the forum.

gene

[gudjeon]

Vapour lock can be gone and instant start up. Fuel pressure not an issue with a bypass filter. Keeps it cool and filter having it constantly circulating. An electrical pump from Napa for carburetted engines and a bypass filter from mid 80's Chrysler spec. The fuel return to the tank via a fitting already provided on diesel tanks or one that can be fabricated. Modern fuel is more volatile in open carb systems. It is formulated to work in High pressure injector set ups.


This is what I did with my old fuel pump,