Warm/hot starting problem

Peter27 · Post by **Peter27** » Thu May 05, 2016 4:51 pm

Tried to post this earlier but think I may have pressed the wrong button..apologies if this is a duplicate.
Since getting the car out of winter hibernation I am experiencing a problem which I did not have when I put it away. When hot it would always start after 2 or 3 seconds of cranking at most, but now (warm or hot) it is taking 20 to 30 seconds (and lots of crossed fingers) or it will not start and I have to leave it for 15-20 mins. From cold it has always started 'on the button' - this has not changed. There is no obvious fuel leak but when accelerating away after slowing down (at a roundabout for example) I am getting a distinct whiff of petrol.
Not sure whether this is related but I fitted a new in-tank pump during the winter (from SNG) - at that time I noted there was very little in the way of dirt/sediment in the tank. Fuel filter is clean. I would perhaps have put the problem down to the carbs drifting out of tune but I am suspicious that the change has been sudden. If the problem was confined to a really hot engine bay then perhaps I would be looking for an ignition problem but it is happening when the engine is only warm. I am starting to wonder if the new pump is delivering fuel at too high a pressure and I am experiencing flooding...? Any ideas where to start (excuse the pun)? Thanks.

cactusman · Post by **cactusman** » Thu May 05, 2016 5:10 pm

If the pump pressure really is too high and overcomes the float chamber valves then you will see and smell fuel dripping from the overflow pipes that run down from the chamber tops and exit somewhere around the oil filter housing. Worth running the pump with the engine off for a few mins and seeing if you can identify the source of the smell as fuel leaks should always get fixed.

I would also be suspicious of your rotor arm. If it is black plastic with the brass arm held with a rivet pop it into the nearest bin and get a red rotor arm. Genuine Lucas arms never had a rivet. Modern copies do and when hot they leak from the rivet to the rotor in the distributor meaning poor starting and eventually ign failure. The classic symptom is starts fine when cold but is a bugger when hot.

Nickleback · Post by **Nickleback** » Thu May 05, 2016 5:35 pm

cactusman wrote:I would also be suspicious of your rotor arm. If it is black plastic with the brass arm held with a rivet pop it into the nearest bin and get a red rotor arm. Genuine Lucas arms never had a rivet. Modern copies do and when hot they leak from the rivet to the rotor in the distributor meaning poor starting and eventually ign failure. The classic symptom is starts fine when cold but is a bugger when hot.

If you have been using a black rotor, then check the contacts in the distributor head are clean and have not been arking out.
Red rotor arm is the way to go.

cactusman · Post by **cactusman** » Thu May 05, 2016 6:20 pm

Excellent tip from Mike too....?

Post by **mgcjag** » Thu May 05, 2016 6:33 pm

Hi Peter....if you think your flooding then befor the engine fires pull out the plugs and look to see if they are wet

caveman · Post by **caveman** » Thu May 05, 2016 7:47 pm

Here's earlier links ref rotor arms etc.

viewtopic.php?t=7619&highlight=

viewtopic.php?t=8783&highlight=

Peter27 · Post by **Peter27** » Thu May 05, 2016 8:10 pm

Thanks to all and I will double-check for fuel leaks with engine off. Rotor arm is red, no rivet and 2 years old. Distributor cap also 2 years old (less than 1,000 miles) and clean on the inside. Plugs a bit sooty (not excessive) but not wet.

caveman · Post by **caveman** » Thu May 05, 2016 8:28 pm

If it was ok before then you may be looking at your new additions.
Go back to basics and pre hibernation. Remove new pump, reinstate original and try it again. If this checks out ok then you've found your answer....new pump isn't quite right. Carbs don't normally go out of tune from sitting there.

Post by **mgcjag** » Thu May 05, 2016 8:36 pm

Hi Peter.....just check that you have a fully charged battery

nyashamun · Post by **nyashamun** » Fri May 06, 2016 2:21 pm

caveman wrote:If it was ok before then you may be looking at your new additions.
Go back to basics and pre hibernation. Remove new pump, reinstate original and try it again. If this checks out ok then you've found your answer....new pump isn't quite right. Carbs don't normally go out of tune from sitting there.

Good advice from caveman. If it was ok before then the problem could be from the editions.

Peter27 · Post by **Peter27** » Fri May 06, 2016 3:41 pm

I can confirm the battery is fine and engine (with hi-torque starter) turns over very well. I will do a bit more investigation this weekend and if that is fruitless, I will indeed take it back to pre-winter spec! I'll post the source of the problem when I (hopefully) find it.

tinworm · Post by **tinworm** » Fri May 06, 2016 4:13 pm

If you take one of the float chamber lids off and it is full of fuel then the pump is not at fault - the car should start . The indications are a crack in the distributor cap or rotor arm causing the spark to track out when the engine is hot as mentioned by others - get a new cap and rotor arm as it is easy and will eliminate this possible fault.

regards Barrie

ps fuel smells in the car can be caused by leaks from the top of the fuel tank
usually from the cable gland on the 3.8 . Barratts fuel pumps suffer from it (so I am told allegedly)

caveman · Post by **caveman** » Fri May 06, 2016 6:02 pm

Good point Barrie, I remember fuel smell inside my car not long after taking delivery. The fuel sender panel situated on the top of the tank was damp were the gasket was absorbing fuel. New gasket sorted it.

Peter27 · Post by **Peter27** » Mon May 09, 2016 11:04 am

I said I would post the solution if I found it, so...

It seems in reporting the symptoms (fuel smell and problem hot-warm starting), I may have put 2 and 2 together and come up with 5! I checked the fuel pump/tank mounting plate gasket but no leaks (unlikely as I had changed this along with the pump over the winter). Then I found a small leak on the fuel-out side of the filter assembly (should have spotted this earlier). This mended I changed the coil (as old one was 12 years old) and then the spark plugs. Result is I now have a car which starts fine, hot or cold. As to the exact cause of the original problem...not entirely sure but I am less interested in the forensic detail of diagnosis than enjoying a car which I can (sort of) rely on to start!

Thanks to everyone for their help and advice. Now have to tackle the oil leak from the rear of the exhaust cam cover. Another reminder perhaps that these cars don't like sitting idle for prolonged periods.

cactusman · Post by **cactusman** » Mon May 09, 2016 4:11 pm

Excellent. Probably a combination of things but so long as it is sorted who cares really.

I would remove the cam cover and replace the gasket and rear oil seal around the blanking plug. Forensically clean the gasket surfaces but no gouging as they are aluminium! A brwnd new stanley knife blade is a useful scraper.
Lots of blue hylomar and carefully tighten. Sure you know but do not over tighten or you crack the cover!!!

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