Technical Starting (not!) again

[AndrewRL]

Happy New Year to all

Sorry for raising another starting question but I am a bit lost where to go next!

As per other posts, the car was starting/running fine until recently. It refused to start and I traced it to a faulty fuel pump. Having replaced that the car spluttered back into life and ran well after I had adjusted the idle and mixture screws but I didn't take it for a drive (owing to the weather!). Weather cleared so I thought I would go for a run but it won't start again!

So...it now turns over on the starter well and does fire up but only with the starter pulled (if that makes sense). When I release the starter the engine splutters and dies. As it does fire I assume it is not a sparking, timing or fuel pump issue so can only assume there is something wrong with the carb??? Jets, mixture, adjustments??

Or should I start somewhere else? I did strip the carb last year and replaced many parts; I also recently adjusted the tappets and replaced the points, condensor, coil, plugs and leads; after all that it ran very well so am not sure that any of those could now be the problem. I have also checked and rechecked the timing.

Any suggestions on possible causes gratefully received

 

[phoenix1]

Hi it sounds like your mixture is wrong ,probably a bit weak.Richen it you can allways turn it back.My 500 L came in bits with a different engine and I havent touched the carb once so I must be lucky.

 

[Duffys Dad]

Try with and without Choke. If that doesn't help then I would remove and blow through the jets. Do you have an inline fuel filter? They are quite sensitive to dirt in the fuel.

 

[Fayray]

I would start by replacing the condenser. I fitted a new one to my car and it failed almost immediately. The symptoms were, after a successful drive, a refusal to start but trying to fire while the starter is engaged and then just dying, much like what you describe.

 

[AndrewRL]

Thanks guys - much appreciated (as always). Have moved one step on and one back!!.

Changed the condensor but sadly little effect. So tackled the carb - checked the filter, main jet, idle jet, cleaned out the float chamber and checked the float and gap. Carried on fiddling with the mixture and idle adjusters and eventually managed to get Luigi to run. However...

The engine will now idle but there is very sluggish response to the throttle. The accelerator has virtually no "feel" and little initial impact. If the pedal is held down or the throttle opened at the carb for several seconds then the revs rise slowly. Definitely not the excellent throttle response there was before all this saga started.

I'm thinking this is either some issue in the carb still or possibly with the new fuel pump that is not getting enough fuel through??? Obviously can't go for a drive yet!

Any ideas where I should look now???

Thanks.

 

[Vitesse]

Tappets is my guess! They tend to have a mind of their own when the car is parked up for winter.

If when you put your foot down on the accelerator and the revs build up really slowly until it will eventually rev much higher. Then it sounds just like tappets. Sometimes playing around with the choke whilst trying to rev the car will improve it and make it rev cleaner.

 

[AndrewRL]

Great thanks...sounds like tappets are next weekend's job!

 

[BambinoClassic]

Not fully clear on your symptoms relating to the response to the throttle pedal but I had what sounded similar - no response or a decrease in revs to initial throttle pedal pressure, then revs would increase with longer / harder pressure on the pedal. Mine was a clogged idle jet that took multiple cleans out over a few drives to persistently be happy. Initial symptoms were stalling at intersections

 

[Duffys Dad]

I have often had a bad condenser which causes problems some time after changing, so your suspicions there may be valid. The only thing to add is that if the Condenser is to blame then it is likely that the points will have worn down or become pitted so it is worth inspecting the contact faces on the points and cleaning with a bit of emery paper if required.

 

[Hobo1960]

Have you checked the distributor advance mechanism in case it's seized or sticking? I'd also check the ignition system to ensure that you're getting a good spark at the plugs.Have you got battery voltage at the coil?

 

[the hobbler]

Many years ago (almost in a galaxy far, far away) my new wife and I went on holiday in my (then) currant 500. We went to Cornwall, which as you all know is not the flattest county in England. We eventually got to the point where everything (and I do mean just about everything!) passed us UPHILL, but as soon as we got over the brow of the hill and picked up a bit of speed, the car would suddenly fly DOWNHILL, and we passed everything that had got passed us uphill. The cause of the problem was a tiny piece of paper--a stamp perforation, that had got into the fuel, and then the carb slow running jet. The brother of one of the lads at work worked in a postage-stamp making company, and everybody made use of this free 'confetti!' It never fails to amaze me what can get into, and lodge in, a carb. Give it a clean out with a proper air-line (as against just blowing through it).
If you do decide the condenser is at fault, either replace the condenser with one of the 'Swiftune' ones (not cheap, but very good, and reliable) or, get rid of the points and fit an electronic ignition, even if it is just a simple 'Hall effect' type (AccuSpark or Petronix):bang:

 

[AndrewRL]

Continued thanks for all the suggestions. I'm afraid I may need more as sadly I'm still no further forward (other than being close to putting an ad in Autotrader!!). I have checked and adjusted the tappets, checked the contacts and they seem clean and also stripped and blown out the carb and jets. I even took off the new fuel pump and removed some of the gaskets in case there wasn't enough push coming from the actuator rod. All to no avail. Of course I can't vouch for doing any of these correctly :-(

So, I still have an engine that will eventually start and actually idles quite well. But when opening the throttle it either just dies or revs rise very slowly/not at all, sometimes with an occasional "pop".

Of course with all this attempted starting, leaving to idle etc the low fuel light has come on :-( I assume that makes no difference (as long as fuel is coming through)???

Any more suggestions would be gratefully received (or if anyone knows a good mobile mechanic with appropriate knowledge in the Cambridge area that would also be useful).

Thanks all.

 

[the hobbler]

Have you checked that you have no air leaks around the base of the carb? One way of checking this is to get the engine running, and then spray something like 'Brake and clutch cleaner' round the BASE of the carb---if the revs alter (most probably rise) it means that there is an unwanted air leak. This is usually caused by either the bakalite spacer warping, and/or the base of the carb warping. The reason that I suggest 'brake and clutch cleaner' is (a) it comes in a spray can and, (b) it can be used (very successfully) as a substitute for 'easy-start'! The cure is to remove carb, and using a sheet of 'wet 'n dry' on a very flat surface (a sheet of thick glass is best), slowly and carefully sand out the warp (keep the 'wet 'n dry' well oiled).
If this proves fruitless, I would suggest that you have a search around for a garage that is au-fait with classic cars and ask them to look at it ("KGF Cassic Cars" are about 40 miles from you in Peterborough). :bang:

 

[F123C]

I agree with Tom ^^.

Although, with an air leak, the engine idle speed tends to be too high, difficult to lower it with the available adjustment and a slight touch on the accelerator may send the revs soaring and be slow to return to (a high) idle.

Also, have you checked the fuel supply to the carb by disconnecting the hose to the carb and spinning the engine on the starter with the hose-end directed into a container. If the engine starts and idles, running for 1 minute should give a flow of approx. 1 pint (500ml). If a non-start, spinning on the starter should give strong spurts of fuel.

Have you ever checked/cleaned the fuel tank? There's a fine mesh strainer/filter on the end of the fuel pick-up pipe inside the tank. This mesh can become blocked, severely restricting fuel flow, regardless of how well the engine fuel pump is working. Check the air vent hole in the fuel cap is clear, there should not be any sound of a vacuum being released when you open the cap (unlike modern cars).

Also, check there's no damage (squashed/ crimped) to the fuel line from tank to pump. You could rig up an independent fuel supply direct from a container to the carb,this will eliminate any problem with the existing fuel tank, filter screen, pick-up pipe, fuel line, fuel pump, fuel pump pushrod, in-line filter. If you wish (given that you have suspicions about the pump pushrod), you could fit an electric pump temporarily near the tank to push the fuel to the carb and bypass the mechanical pump at the engine with a longer length of hose.

Insufficient fuel can give symptoms similar to an air-leak, difference is the engine can usually be made to rev-up with an air leak but not with a fuel shortage. Tom ('the hobbler') above, suggests spraying brake cleaner or similar combustible spray around the carb base, I'd suggest you also try spraying it down the carb intake while trying to rev the engine by opening the throttle. You can also spray/dribble a little petrol into the carb. intake to see if the engine can be made to rev-up.

Have you changed anything else on the car since it last ran ok? (apart from the fuel pump).

Could you have dislodged/disturbed something while checking things out?

Is the fuel clean, free from water and not too old?

Each time you cleaned the carb, was there a normal amount of fuel in the float chamber when you removed the carb. top? ( probably 1/4 - 1/3 full with the float removed,is normal). You might have to try cleaning the carb yet again if nothing else makes any improvement.

The only other thought I've had is that if this was an OHC engine with a timing belt , I'd be suggesting checking the valve timing hasn't slipped. But this is highly unlikely on a Fiat 500., could really only go wrong if timing chain was replaced incorrectly or a woodruff key sheared.

AL.

 

[F123C]

I'd caution against engaging a Mobile Mechanic unless he/she is 'old-school' or very familiar with classic cars, preferably with the Fiat 500 (the 'old' one!!).

A Mechanic is going to check for a good spark and that it's occuring at the correct time.
He's going to check for fuel reaching the carb. If not, he'll probably blame the fuel pump (the one you've already replaced!). Or maybe the in-line filter. Having changed/by-passed that, he'll then likely suspect a blockage/severe restriction somewhere between the tank and the pump.....

If fuel is reaching the carb, he's going to suspect a blockage and clean the carb again..... Maybe he'll know what to look for in a Fiat 500 carb... Or not!

Or he might then decide that the ignition system is faulty, after all, and start changing the parts you've already replaced.....

He might remember to check compression pressures. Might not be happy with the results and tell you that you need a new engine, just to get away from this job.

Other that another 'pair of eyes' on the problem, he's not likely to do anything for you that members here can't.

Best solution imho is, if possible, try to get someone knowledgeable with working on older cars to drop by and accompany you through all the points suggested in the above posts.

Regards,

AL.

 

[AndrewRL]

Hi all (most recently Tom/Hobbler and AL/F123C)

Thanks for the suggestions...some new things to try.

I will try the spray and see if there is any evidence of air leakage (I did fully strip/service the carb mid 2017 including new drip tray and gaskets and did check for a warped bottom then but am willing to try anything now to work out what is happening (or not!).

I will try and check the tank too but the pipes seem OK (when the issues first started I checked by blowing back up the pipes and bubbles came out in the tank); there does seem to be a good flow out of the new pump into the carb but will take the pipe off and check what happens when the starter turned.

To do the "independent" fuel line check - how do you rig that up? I don't have any electric pumps to use. I guess I could put a pipe into a container near the engine and connect that into the pump - at least that would check whether there was an issue between tank and pump (??).

Another ignoramus question - your reference to "carb intake" - what do you mean exactly? The pipe inlet? The air inlet?

In answer to your other questions:
- the car was last driven at the end of November, had a couple of weeks in the garage and then wouldn't start (I don't find many free weekend days to work on the car and several were taken up identifying and rectifying the fuel pump issue);
- the only things I have replaced are the fuel pump, spacer, gaskets and plastic fuel lines; obviously I have tinkered with other things to try and get this sorted (tappets, carb, timing)
- the petrol is fairly new (November)
- when I have taken the top off the carb the float chamber is about 1/3 full

You are also right about "help" and mechanics - I know a mechanic will just go through the steps/questions that I did and will just want to plug the car into a computer . You guys (and ladies?) on this forum are a godsend and have so far got me out of most issues. As a novice it would just be nice to have someone to watch/advise/hold my hand when I get really stuck

Anyway, a few things to try next and, fingers crossed, the problem will become evident.

(What worries me is that one of the reasons I want the car driveable is to investigate a grating noise from the axle I heard when the car was last driven....so getting the car running is, sadly, just the start of more questions I suspect )

Thanks again...and if anything else comes to mind, feel free to let me know!

 

[the hobbler]

Andrew, there is an ex-forum member in the Cambridge area (he has gone over to the dark side--Range-Rovers!). I will contact him and see if he will give me permission to pass his e-mail address over to you---he might be prepared to 'hold your hand'

 

[AndrewRL]

Thanks. Is that Steve? If so, he did help me out when I first got the car but he sold his 500 shortly afterwards so I haven't liked to trouble him. I'm not sure I still have his contact details so if you think he could help (and be willing...I fully understand if he says no!) then thank you for getting in touch with him.

 

[F123C]

Hi Andrew,

I'll try to answer your questions.

By an 'Independent Fuel Supply', I mean a separate container of fuel to supply the carb. You could do as you suggest - a container of fuel connected by a hose to the fuel pump.

I prefer to use an old lawnmower fuel tank (with a tap) or a commercially available unit as used in motorcycle workshops to provide a gravity feed of fuel to the carb, just suspend it a couple of inches higher than the carb, too high and it may overwhelm the float valve resulting in carb flooding. This way, eliminates any possible problem with the fuel pump and in-line filter, but your way is fine. You could use a simple bottle with a hose attaching it to the carb to do the same job. (No need to buy special equipment for a temporary one-off job).

By 'Carb Intake', I mean the air intake, i.e. the top of the carb. Some people refer to this as the choke (can cause confusion) or venturi. Sorry for any confusion I may have caused.

Your float chamber approx. 1/3 full when top cover is removed sounds about right. This also suggests that your fuel pump is working ok.

If the engine won't rev-up, try covering most of the carb. air intake with your hand to enrich the mixture. If you can get the engine to rev-up, as you close the throttle, cover the carb air intake fully with your hand as the engine slows down. Repeat this a couple of times. Iirc this applies a greater vacuum across some of the jets and sometimes clears a blockage.

Regards,

Al.

 

[stevehg]

Hi Andrew

I got Tom’s email, and I’ll pm you with my details.

Old school engines with distributors, coils and carbs are not my area of expertise, so I’m not sure how much help I’ll be, but a new pair of eyes and helping pair of hands are available.

I do have a working (well almost 2 years ago) std 500 engine and gearbox you can have here and we can use pump, carb, distributor to eliminate things, and once yours is running the box may come in handy for your potential driveline issue.

cheers, Steve