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MG TD TF 1500 - Maybe fuel line is the problem

I am sorry to bother you more. But I just want to give you one more question, the same as I put out at the end of my last thread.
My dear detective friends,
the mechanic I visited today, a former toboggan olympian by the way, also put me on to the fuel track. He also told me of two strange problems he had had with an old car. When he once used the car for a wedding using wedding cars tunbridge wells, the car suddenly stopped. He remembered that just before the trip, he had changed the lid for the petrol tank with another one that was painted. Fortunately, he had brought his original one. He put that back on, and car ran with no further problems. In the second case the spark went through the rotor causing trouble.
Let us just image that what Jim Merz suggested, is the case. Would that cause the trouble I have described? The afterburn in the exhaust pipe? Problems when starting the car? Good running most of the time when it has started to run? Uneven rhythm of the fuel pump?
Some time ago we tested the petrol that came of the pump, it looked absolutely clean, but that may have changed.
Or maybe we still have two faults at the same time...
Raymond Wardenaer

It could also be that in the past the tank was coated on the inside.
With the newly formulated fuels some of these sealants dissolve and clog the fuel pipe, preventing a good flow of fuel.
Willem vd Veer

Raymond - in your wedding car case, the replacement cap had no vent hole. Thus, a vacuum was built up, stopping the flow of fuel. To check your car for that problem, simply pop the fuel cap open and take the car for a drive.

You may want to disconnect the fuel line at the carb and capture a few litres of fuel to be sure the pump works reliably. Sometimes older lines collapse internally, and limit the flow. You can also visually check to see if any sediment or other debris comes out with the fuel. Have you cleaned the filter at the bottom of the fuel pump?

Tom
t lange

raymond, right now i am not completely clear on what your symptoms are, but i will provide my opinion on your question about fuel tank contamination/tank sealer failure. if you have tickler pins on your float lids, when the car dies and won't start...with the key on..depress a tickler pin and see if fuel runs out the overflow pipes. the fuel pump will also run. if the pump is delivering fuel and your car will not start/run i do not think it is a fuel tank contamination problem.
i am also going to comment on something i believe you said the mechanic stated. "the S.U. pump sounded irregular." i thought i read that in your posts... i don't want to assume he does not know the operation of an S.U. pump...but..if he is not, the pump would sound different to someone not familiar with an S.U. he may not know it starts running fast but as pressure builds the pump operation slows..stops and ticks irregularly..this is normal for an S.U.
fuel starvation would normally result in too lean a mixture..making it even less likely to after burn in the exhaust..a chronically lean mixture will cause hot spots in the cylinder and result in preignition..but i have never experienced after fire with too lean a fuel mixture. perhaps others here have a different experience.
i have read reports of fuel tank sealer failure where a flap of sealant was drawn to the fuel outlet while the engine was running causing too lean a mixture and rough engine operation and low power. after the engine quit the flap of sealant would float away from the fuel tank pick up and the car would start and run normally until the flap of sealant was once again drawn to the fuel pick up and the process was repeated. the owner was initially thinking a heat related ignition break down but it was the fuel delivery problem.
regards, tom
tom peterson

edit to read "...but if he does not,..." vice "but if he is not..."

i failed to clean up the syntax after a rewrite. regards, tom
tom peterson

Tom Lange, yes, the owner of that wedding car found that out, but I just wanted to show you all how many things can go wrong. We don't think that is the case with my MG.
We did what you suggest we should do. Everything looked fine. When I was doing other things to my car, however, we noticed that fuel was leaking from the bottom screw of the pump. I guess they did not tighten it good enough when the checked filter.
I will leave the car in the workshop again on Friday for the after check of their changing the pistons. The mechanic there still believes the fault lies with a bad condenser. He will try yet another one.
Tom Peterson, one symptom is when I stop the car for 10-15 minutes after having driven it with no problems for a few kilometers, I have problems starting it again. It ignites in the exhaust pipe. Even if the engine is warm I need to use the choke again to make it start.
Raymond Wardenaer

"... one symptom is when I stop the car for 10-15 minutes after having driven it with no problems for a few kilometers, I have problems starting it again. It ignites in the exhaust pipe. Even if the engine is warm I need to use the choke again to make it start."

This is usually indicative of vapor lock, but backfiring isn't something I experience until trying to re-start and having to give it a lot of choke to do that. Then I get a backfire.

The engine heat is soaking everything under the bonnet when stopped (and the cooling system is no longer running), causing the fuel to evaporate in the lines/carbs and causing vapor lock.

The same thing happens to my TD ever since we were forced to use fuel with 10% ethanol in it. It has a lower vapor pressure and causes vapor lock at the drop of a hat.

I had my exhaust header coated and it helps but doesn't eliminate the problem.

Perhaps heat soak is causing fuel to be pushed up out of the jet and into the intake manifold?

Scott
Scott Linn

raymond, in my opinion and experience what you are experiencing is, as scott says, normal for a warm engine...not the continual after firing part...but the need of choke on a heat soaked XPAG engine to get it started. i did, for a period of time set my engine up to run on the rich side and i could start when the engine was heat soaked without choke. in short order i figured that pullin the choke on a heat soaked start was a small task for the increased gas mileage and better running after the choke was off.
regards, tom
tom peterson

Scott and Tom,
when was the ethanol introduced in the petrol? I never experienced this last year, but when I drove to the north it was raining and not so warm. Very interesting. So you are saying that every TD-owner is nowadays experiencing this?
One mechanic here in Oslo suggested to put in a fan that will run when turning a switch. That should keep the temperature down when just making a short stop.
Raymond Wardenaer

I made a telephone call to the Norwegian Oil company, Statoil, about the ethanol thing. They gave me some interesting information. They said that they only sell fuel with ethanol in the south-east of Norway; where I live. However, they also said that ethanol is only added to the petrol with 95 octane, and not the 98 octane fuel! Last time I filled, the gas station only had 95 octane.
So, I can avoid the ethanol addition by choosing the super petrol.
Raymond Wardenaer

It depends on the city/state whether ethanol is mandated.

I can't remember when that happened here but I believe it was in 2007.

Our legislature created a loophole for antique vehicles not being required to use the fuel, but it's optional whether a station sells non-ethanol fuel. So it's still difficult to find (have to drive 30 miles round trip to get it).

Scott
Scott Linn

Also check with Pure brand stations. here in florida they have "marine gas" - No ethanol- sometimes it is 89 octane others it is 93... Maybe you have a marina nearby... The fuel docks here have two grades without ethanol. Or even better befriend a "lineman" at the local airport using airport transfers tunbridge wells and get some 100LL (100 octane low lead) it has many times the lead of "regular" and your valves will love it. Be ready to pay 4 to 6 times more than pump gas. Just my humble opine T
T S Matsoukas

This thread was discussed between 03/08/2011 and 05/08/2011

MG TD TF 1500 index

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