Coughing and Spluttering - Pinto 2.0 Petrol - Weber 34ICH

[rik007]

Hi, anyone shed any light on this one?

Have a SWB Mk3 Transit with bog standard 2.0l Petrol engine, but with Weber 34ICH carb.

On the whole the engine has run just fine, it got 100k now but I think its pretty sound.

Recently its been coughing and spluttering all over the place, am getting fed up now trying to find the porblem so thought I'd ask.

Thing I have done:

1. Fairly new plugs last year and seem OK

2. Checked the timing with strobe and set to about 2degrees BTDC as per manual for unleaded.

3. HT Leads failry new i.e. last year

4. Cant see anything obvious wrong with dizzy

5. New rotor and dixxy cap

6. Cleaned Weber 34ICH endless times, even phoned weber to see if I had correct jet i.e. a 165 and they say this is correct.

7. New fuel pump

8. Checked value gaps a couple of months back and they seem OK.

9. Changed cambelt last year, but have over 2k miles trouble free so think this is OK


Now oddly I took the transit to a garage and they stuck a pipe up the rear end and said it was running way to lean. Which seems about right, if I pull the choke out I can just about get it along the road a bit; but its all very tricky to keep the thing going.

Its just a pain the buttocks now, I 'm about to call the scrappy and get them to take a decent van away!!!

Aany help any one?

Cheers,

Rich.

[winterheating]

Could you not have a leak after the carb, inlet manifold or something if its running lean?

fuel filter ok?

[FredTransit]

What year van is this in?

[rover]

Start with the basics.. get a can of wd40 or similar and use the straw, spray around all the joints (manifold to head,manifold to carb, carb spacer etc.) if theres a noticeable difference in the tone of the engine then you have an air leak. It may be that the carb simply needs adjusting.

Just because plugs/leads look ok doesnt mean they are!

Rover.

[rik007]

Its on a : 1988 SWB Transit 2.0l Pinto

Weirdly this evening, really went to town and cleaned the carb.

Put it back on and it drove like a dream ie. as it should; thought I'd cured it.

After about 5 miles started coughing and spluttering again!!

Stopped a few miles later then started it up again and all was well!

I'm wondering about air locks? Or may be fuel line? Or petrol tank venting? Could still be something electronic.

Its a really weird one.

Have given up tonight... will have a crack at it tomorrow.

Rich.

[rik007]

Well, I've taken the petrol tank off.

Both vent pipes have kinks in them... so am wondering if there is a problem allowing air back into the tank.

HOWEVER....

I also took the filler pipe off from the side of the van to the tank. Seems the vent pipes are simply connected to the top of the neck of the filler pipe!

But when I put the petrol cap on the pipe as it would be normally, hold my hand over the large open end and blow/suck the vent pipe its almost impossible to draw any air in!!! Hmmmm what allows the air into the tank when then engine is running and petrol is being drawn off?? Does is come in via the filler cap?? If so its am extremely small amount of air that is allowed into the tank!

As the vent pip is plumbed into the filler tube and effectively the petrol cap seems to block entry of anything down the neck as I guess you would expect.... how on earth does the tank vent? Is this the cause of a vacuum in the petrol tank that’s stopping petrol being drawn up by the petrol pump???

Any thoughts on this appreciated,

Richard

[rik007]

I took off the vent pipes which had various kinks in them.

Put them in some boiling water and hey presto they return their orginal form.

So put them back on the tank, so I guess the tank is now breathing properly!

Also checked the valve gaps last night all seem OK.

But still it seems to falter along.

Clear tank as far as I can see, clear supply pipe, new petrol pump, timimg OK, checked the plugs, cleaned the weber carb.... still drives like a dog.

Please tell me something like a daft git I 've missed!!

R.

[rover]

Coil? Ignition module? Checked those?

Rover.

[rik007]

Well whos a bloody idiot then?

ME

..... as if I hadnt had this before!

Its the valve setting again!!

What a plonker.

I had check them about a month ago... as was sure it would'nt be that.
But after taking the tank off, sorting the breather tubes, checking timing, plugs, leads, endless cleaning of the carb, even a new 170jet in the weber cab (instead of reccomended 165jet).... it was the valve gaps all along.

I guess the real moral here might be that on a 100,000mile engine things get worn. So by being over diligent with getting them exact they may acutally be getting set overtight? i.e perhaps the valves move up the seat slightly just enough to hold them open a tad???

Anyway.. its runs like a beaut now!

(even runs better on LPG as I've just put an LPG system on to it, smooth and fast as you need, starts easily and now a 40mpg equivalent!)

Cheers,

Rich

[rik007]

quick update on this one for anyone whos interested....

i had the rough running problem come back over the past few months, again i tried everything in the book as i thought i'd solved it with the valves being tight

however it turns out the carb had some dirt in it! i spent ages trying to clean it and blow through with an hp air hose to boot, but eventually admitted defeat and sent it to my local garage. all they did was clean the carb again and they said it had some crud still in it. an hour later i collected it and it runs as sweet as a nut!!

i have an ich34 weber on the engine, not rocket science but i guess one of the small tubes was blocked. quite how the garage did it i dont know but there you go if you have a weber it might need a good clean!

[vanfox]

One thing not mentioned here is carburetter icing. Don't laugh! Been there, got the T shirt. If you don't refit the warm air collector from the exhaust manifold to the air intake and check the flap valve is working then in certain atmospheric conditions the carb may become restricted with a build up of ice. This will appear as extremely rich running, black smoke, a terrible missfire and no revs at all. Just stop for 5 mins whilst the heatsoak from the engine melts the ice and way you go, 'till it happens again.