Hard to start Hot

[timc930]

Having a Hard to start hot issue, so today I bypassed the mech pump and installed a Facet Electric Pump, pulled the carb, took apart, let soak in carb cleaner for a couple hours then reassembled, installed the carb and truck fired right up. I let it idle for around 30 minutes to get good and hot, shut it down, waited five minutes and will not restart. If I hold my hand over the carb body while someone is cranking, I can usually get it to start. Also replaced the coil as well. Weber 34ICH Carb.

[SafeAirOne]

Well...if I were sure it's a carb problem, I'd start by looking for either an air (vacuum) leak at temperature or a fuel flow restriction at temperature, or, less likely but possible I suppose, a vapor lock issue.

Take this with a grain of salt though, since I don't use carburetors myself.

[timc930]

This may be a feed issue, as it fired right up this morning, let it run, shut it down, then it would immediately restart. Once I waited 10 minutes, it would not. I could hear the Elect FP running trying to reprime (pump is loud until it has it's prime), it wold not reprime until I removed the fuel line form the carb, then it began to flow. Going to check the lines coming from the tank.

Regardless of the above, there was fuel in the carb bowl, so it should be starting warm/hot, that's what is puzzling.

[timc930]

So there is nothing restricting the fuel flow to the carb. Looked in tank, very clean. Blew threw the lines. Today, I let the car idle for about 40 minutes and it just shut down. Fuel pump kept running (electric and wired to ign switch) but was very loud because it was not pumping fuel. I have no idea what is could cause an elect pump to all of a sudden loose the ability to pump fuel. Once car cooled off it fired up on first crank.

The car acts as if once the engine gets hot, the fuel becomes a vapor, and the elect fuel pump and the carb are unable to function until the engine cools.

[SafeAirOne]

It sounds like the fuel pump is being starved of fuel. Is your tank properly vented? Does the sound of the starved pump change when you remove the fuel filler cap?

Is the sediment screen on the bottom of the fuel pickup tube clean? Is there an internal sediment screen in the electric fuel pump?

[timc930]

It sounds like the fuel pump is being starved of fuel. Is your tank properly vented? Does the sound of the starved pump change when you remove the fuel filler cap?

Is the sediment screen on the bottom of the fuel pickup tube clean? Is there an internal sediment screen in the electric fuel pump?

No sediment blockage anywhere in system, carb pulled apart and cleaned this week, tank clean, all fuel filters perfectly clear with no sediment what so ever.

Tank is not vented, and I tried removing the cap several months ago when I was working this, but that was with the mechanical pump. But you are exactly right, it does act as if there is vacuum pulling against the fuel flow....

How should the tank be properly vented?

[Les Parker]

You could have a bad fuel cap. It should have a small hole for venting on IIa's and a vent valve on the Series III.
Try it will the filler cap removed.

[timc930]

Looks like it was a problem with venting, creating a vacuum all the way to the carb, as there was fuel in the bowl and it still would not start. Removed the gas cap, so far so good. I have drilled 2 1/8 holes in the underside of the cap....

Been running it all morning, getting hot, shutting down, waiting 5-10 and it has fired right up each time. Drove it a few miles did good. We'll see how it goes....

tim

[bugeye88]

Tim,
Great! Glad it was something so easy to fix. I've seen that happen in modern cars with their complicated fuel systems, but not often with Landy's. At least now you have all the jets in the carb clean and a good electric pump in place.

Cheers,

Rob
Bugeye88

[SafeAirOne]

I have drilled 2 1/8 holes in the underside of the cap....

Two and an eighth inch-holes? Wow, it's REALLY vented now!



Nice job. This is a well-known issue to me, unfortunately. My issue is always a clogged up sediment screen on the bottom of the fuel pickup tube though it's is essentially the same problem as a bad tank vent. Glad it was an easy fix.

[timc930]

Two and an eighth inch-holes? Wow, it's REALLY vented now!



Nice job. This is a well-known issue to me, unfortunately. My issue is always a clogged up sediment screen on the bottom of the fuel pickup tube though it's is essentially the same problem as a bad tank vent. Glad it was an easy fix.

2 holes 1/8 each!!

yeah been running it all day and no problems at all....

Funny thing, i've been fighting this for the last couple of months and pulled the gas cap this summer and it made no difference at all...i just installed a FP regulator and set it at 2.5 lbs since the elect FP puts out 4-7.

[timc930]

Tim,
Great! Glad it was something so easy to fix. I've seen that happen in modern cars with their complicated fuel systems, but not often with Landy's. At least now you have all the jets in the carb clean and a good electric pump in place.

Cheers,

Rob
Bugeye88

Yeah, I think I am good to go!!!

[timc930]

Yeah, I think I am good to go!!!

So Actually I am back to the problem. Drove it today first time since TG week, and after driving for about 15 minutes started loosing power, then it just shut down as if it ran out of fuel. Fuel in the FF, but when I pulled the line off the carb, no pressure. Usually I get a bit of spray. Turn FP on to see if fuel was flowing, and it was. Connected fuel line back up, took gas cap off, and truck fired right up. Turned around to drive home, and after 5 minutes starting acting as if it was not getting enough fuel, would not take full throttle (gas cap still off) so I had to drive slower and slower as if fuel flow was reducing, as if a vacuum was slowly building reducing the fuel that was able to get to the carb, but gas cap was completely off.

Truck act's just like once it's started, there is slow vacuum building, slowly reducing the fuel flow to engine, with eventually preventing fuel from reaching the combustion chamber, but I have the gas cap off so I don't really know where the vacuum could be building.....





So,, just thinking here, when I was driving flat out (approx 60mph) as the truck started to loose power there were one or two very loud backfires out the exhaust, which to me always means to much fuel. I am wondering if I may have just the opposite, with the engine flooding due to sticky needle seat etc etc. Also, when I shut the truck off after a hard run, I always get one large backfire out the exhaust after truck shuts down....

I have pulled the carb apart several times, (and just recently soaked in CC) to check the N&S, with no apparent visual or operational feel of a problem, but mpg has always been low double/high single digits since I have owned this truck....

tim

[o2batsea]

Backfire usually indicates timing is off. If it were me I'd stop throwing love at that carb and order up a new one.

[SafeAirOne]

The engine dying really does sound like a fuel deficit situation. Poor venting is only one cause for a fuel deficit like this. The other cause is a blockage upstream from the fuel pump(s).

Which electric fuel pump do you have? There are filter elements that can get clogged up in the stock Facet fuel pumps that came on 109 wagons:



Re-check the strainer screen on the bottom of the fuel pickup tube in the tank. Every time that my rover exhibits the exact same symptoms you describe, the strainer is plugged up with new debris from my increasingly rusty fuel tank. I generally scrub it with an old toothbrush then blow it out by putting my the nozzle of my blower into the uplift tube hole and gently (at first) blowing OUTWARD, clearing the screen completely.


As for the backfiring...I think that's a different issue. Backfiring out of the EXHAUST is often a leakage issue with the exhaust manifold or downpipe, combined with unburned fuel in the exhaust stream. Backfiring out of the CARB is often an issue with a hot spot somewhere in a cylinder or poor ignition timing or poor valve timing.

What do your spark plugs look like?