Fuel Starvation?????

[ch33kster]

Hi guys,

I've been having major issues with my 69' Spider.

Last summer I drove to Le Mans classic in my Fiat, the first lengthy journey she had
been taken on since a full rebuild over 3 years ago. Plenty of mileage had been covered
prior to this journey without any issues.

The car would start jumping and jerking and then stall after 30 miles or so after crossing into France.
The engine then wouldn't start. At first I thought it was fuel evaporation due to the hot weather and
running temps. or bad fuel.

After letting the engine cool it would fire up and would be OK for the remaining journey.
The following day it would be constantly jumping / stalling.

I checked the Fuel filter to make sure it wasn't clogged but replaced. Blew air through the fuel line to
check for blockages. Checked all spark plugs, disi cap and points etc.

On returning to the UK, I removed and checked the fuel tank to see if there was any debris, it was clear.
Checked the mechanical fuel pump and diaphragm which seemed OK but replaced it all the same.

After all these checks had been made, I drove the car but it still continued to kangaroo and stall.

My afterthoughts are that it could be my Carb which is the original Weber 26/34 DHSA.

Very frustrated and crying out for help.

Your assistance and help, as ever, is always fantastic.

Cheers,

Charles

[majicwrench]

Are you sure it is a fuel issue,or are you guessing it is??
If you are sure it is a fuel issue, it is very possible the tank is not venting properly. Which means as fuel is sucked out, a vacuum begins to build in the tank, till the pump can no longer suck fuel from it. THis generally take a bit of running. And system will generally leak enough air back into tank to run again after a sit.

Had a Firebird 30 years ago that actually collapsed the tank from the vacuum created by the fuel pump.
When it begins acting up, you may wish to remove the fuel tank cap.

Not likely carb.

Test test. When it acts up, try checking fuel delivery.

[joelbert2k]

I agree with majicwrench. I had a 70 coupe that would behave the same way, although it usually took half a tank's worth of driving to create the problem. I also cracked the tank before I found the problem. The dealer never could figure it out and after the tank cracked and started leaking he accused me of backing over something.
To verify that this is the problem fill the tank and drive until it stalls or start jerking. Then remove the gas cap. If you hear a big whoosh of air then that's the problem. There is a 3 or 4 way valve in the venting system that is probably clogged. Mine was installed wrong from the factory.

Joel

[Five40iguy]

If you feel you haven't yet fixed your problem, check the canister inside the trunck quarter panel on the left side of the trunck above tha gas to see if any hoses have come off or if it's clogged. (At least thats where the canister is located on my '70 spider). It may be blocked, it may be faulty engineering, who knows. I installed a low pressure electric fuel pump inline so when I feel there's a problem I just switch it on and we are good to go. If you wish the car to remain "virgin" I'd check that purge valve/canister/whatever you wish to call it. I'm sure it accomplishes the same thing as the vent hole in the gallon gas can you fill your lawn mower with. (You know, if you have the hole plugged the gas runs a while and then starts to "chug" until you unplug the hole and the fuel runs freely). Regardless, all the best and hope your next trip will take you down the French Coast and Italy on your return.