mech fuel pump

D

Duncan

True Classic
Hi been having problems with my car running - I've been told by forum members that the likely problem is crud in my carb.

I'm a bit daunted by dismantling a carb so I'm checking that everything else is ok before I go down this road.

I wonder if my problem may be with the mechanical fuel pump, the haynes manual tells me they have a filter in them - which may be clogged. My mech pump looks nothing like the dome shaped one in the haynes manual - mine is the one which is fitted on all later cars. Does this type of pump have a filter and if so how do I remove it?

Regards.


Duncan
 
Isn't your car pouring black smoke and refusing to run except under full throttle???

If so, it's getting too much fuel instead of not enough. Kind of unlikely to be a clogged filter in that case, don't ya think? Sure, you might have clogs all through the fuel system if your tank is falling to bits, but you could remove every trace of the debris and the car would still run the same way if it's getting too much fuel already. Maybe worse, in fact.

I have a hypothetical question for you: if you misplace your keys and everyone you ask about them tells you they're in the kitchen, do you start looking in the living room? Just wondering.... ;-)

///Mike
 
Thanks Mike but.....

I cleaned the carb monday - with carb cleaner, removed and cleaned jets. I also switched carbs with my spare and got the same result i.e. had to put foot down to get the thing to go. Could not see any smoke but there maybe only get that underload.

Not to say my spare carb is not in a similar state to the one on the car - it was untested.

Also cleaned spark plugs, changed HT leads , rotar arm in dizzy.

So will bite bullet and dismantle a carb

Regards

Duncan
 
Wait a minute! If it's not smoking then it might well be something else, such as a lack of fuel.

First off, have you replaced the fuel filter? If not, do that right away. If possible, cut the old one open or at least tap the inlet against a hard surface to see what comes out, if anything. That could be an important clue.

Just spray cleaning the carb won't do much if you have a clogged jet. You'll need to remove and disassemble the jets to clean them properly. Check them visually for any tiny bits of trash. That is usually the cause of this kind of problem in a carbureted car, and where we would usually tell you to start. It was your mentioning black smoke that had us thinking the carb was somehow delivering too much fuel (which might be the case still).

If you happen to remove the top of the carb, at the very least remove the float and pull the needle so you can examine it, as well as the seat for signs of trash. That's the most likely cause of the engine getting way too much fuel.

Going back to your original question, is it possible that you have an electric fuel pump instead of the mechanical one?

In either case, rather than dismantling the pump in hopes of cleaning it as the first course of action, try checking the output from the pump before jumping to any conclusions. Disconnect the inlet line from the carb and run it to a non-breakable container (a coffee can works fine as long as it doesn't leak). Then spin the engine over and see how much fuel comes out of the hose. Helps to have assistance but you can do it alone if need be. But make certain you do this outdoors, well away from structures, and with plenty of rags and a fire extinguisher nearby.

I'm on the way out the door but there are a few quick ideas to try before jumping in too deep. Hopefully others will chime in soon. Report back with what you find and we'll try to offer more ideas.

Or you can call the Xweb tech line at 1-900-POP-TONY. $1.99 a minute for the first minute, $5.99 a minute thereafter. ;-))

Cheers,

///Mike
 
Sometimes the only way to sort these gremlins is to remove the carb as a whole, carefully dismantle it, and with patience and one or two cans of pressurised carb cleaner and a service kit completely blast any microscopic crap that might live inside it.

Pulling jets and cleaning them may solve the issue short term but if there's bits of crap in the lower carb, eventually the jets will find them again and again.

I entrusted my last carb nightmare to a local garage who made a right mess of it. Charged me for a new fuel pump and it was simply a rotting cork carb gasket that came with the K&N that was crumbling and dropping into the carb. Only way to fix was to totally flush the carb with carb cleaner and compressed air.

Good luck with it. It just takes patience and more patience!

Regards,

Mickey
 
Not ta gang up on ya...

But both ///Mike and Mickey have some good points.

ALso, TOO MUCH fuel can also mean POOR ATOMIZATION, or DRIPS and DROPS instead of a nice neat spray... which usually comes form clogged Metering Rods and Emulsion Tubes. It will cause terrible stumbling and black smoke also.

Here is a "typical drawing" of a carb SIMILAR to yours...

http://xwebforums.com/wiki/images/6/67/34DMTR.pdf

Note items 9-13 in the drawing as these are the rods and tubes that foul (two each, three total shown in drawing, 9, 10, & 11 make up one, 12 & 13 another... and 12 & 13A make up a slightly different type.) with little black bits or slimy black crud. The crud also gets into the passageways that these screw into. That is why it is imperative (and BEST) tha the carb is SOAKED in carburator ACID and then neutralized and blown out with high pressure air.

Do unscrew most all the parts but so not attempt to pull the butterflies or shafts. If careful, you can re-use all the parts and gaskets without buying a kit.

Hope this helps...

Also note 14 and insure its is clear... It pull straight out and I just blow through it!
 
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you may have solved your problems by now but I just thought I would add my 2 cents worth. I had a similar problem to what you discribe and it turned out to be an easy fix. simply remove the air cleaner and blow out the air correction jets you see near the throat of the carb. pull each one out blow clean then replace. this solved my running issues instantly. the crud comes from the crank breather so I also removed that and clean it up to stop it happening again.
 
Timing marks.

Check the timing marks to see if the crank and cam are in sync. I have seen cars run the way you suggest because of slipping 4 teeth.

Also the exhaust system may be plugged which would also cause similar symtoms.

TonyK.

Grimsby Ontario Canada.
 
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