The Triumph Dolomite Club - Discussion Forum

After fitting a new fuel pump which I thought was the problem I broke down today. I started the car and left it to warm up and then drove 2/3 miles and it drove perfectly, did some shopping and started on my journey home and after about a mile the car wouldn't pull and eventually died. When I tried to start it it seemed to be running on two cylinders and wouldn't rev. After checking to see anything obvious I called the breakdown service, because being a automatic I couldn't call my son for a tow.It was about an hour when the mechanic arrived and low and behold it started and ran perfect all the way home. So any ideas what it is? Any help appreciated. The breakdown people ( Green Flag ) sent a text saying they would not come out again for the same problem for the next 28days.
The car is a 1972 1850 dolomite with electronic ignition so it can't be the points or condenser. It had a new rotor arm and new plugs recently. My only thought is it could be the coil, it's obviously something that is breaking down when it gets warm or hot.
If it is the coil what type do I buy? Originally it was fitted with a balance resister type but somebody has converted it to a straight 12 volt one.
Sorry to go on.
Alan

Best coils are genuine bosch ones, I think used by early nissan micras and others.
Intermittent faults are a pain, if the car does it again you need to check for a spark, then if the EI is working (can't think how to test that, except by substitution)

have you checked the float bowls and floats are operating correctly?

TrustNo1 wrote: ↑Fri Mar 19, 2021 8:15 pm have you checked the float bowls and floats are operating correctly?

No I haven't been any where near the carbs but I will check tomorrow. I have checked after fitting the new Pump for leaks but all seemed well.

alvera wrote: ↑Fri Mar 19, 2021 9:15 pm

TrustNo1 wrote: ↑Fri Mar 19, 2021 8:15 pm have you checked the float bowls and floats are operating correctly?

No I haven't been any where near the carbs but I will check tomorrow. I have checked after fitting the new Pump for leaks but all seemed well.

I had a similar problem a few years back and it was the coil, it got very hot when this happened , as Trust said also check the floats

I had the same problem several years ago and it turned out to be a very small hole in the petrol pipe where it goes up and over the rear axle. As the pin prick hole was above the top of the petrol tank petrol it would not leak out when the car was standing, so no smell of petrol. My assumption was that the pump would draw in air through the pin hole, again no petrol would leak out so still no smell of petrol when the engine was running. I only managed to find it when I was under the car and about to take the petrol pipe off the tank connection to check if the outlet from the tank was blocking up. The car had just cut out and I was looking around and noticed that the petrol pipe above the rear axle look wet where it was bent. When I touched it I could smell it was petrol. My assumption is that when the engine stopped there was still some petrol in the pipe and this is the only time what any petrol escaped.

As well as the coil, might be worth considering the condenser breaking down when hot. I had a bit of trouble with newer replacement ones.

What I thought was odd was that when the engine was misfiring and running like a bag of whatever, the rev counter didn't show the problem.

Currently running with one from the distributor doctor, and had no problems since fitting that.

Graham

GrahamFountain wrote: ↑Sat Mar 20, 2021 7:03 pm As well as the coil, might be worth considering the condenser breaking down when hot. I had a bit of trouble with newer replacement ones.

What I thought was odd was that when the engine was misfiring and running like a bag of whatever, the rev counter didn't show the problem.

Currently running with one from the distributor doctor, and had no problems since fitting that.

Graham

Graham this car has electronic ignition fitted

mahony wrote: ↑Sat Mar 20, 2021 7:15 pm

GrahamFountain wrote: ↑Sat Mar 20, 2021 7:03 pm As well as the coil, might be worth considering the condenser breaking down when hot. I had a bit of trouble with newer replacement ones.

What I thought was odd was that when the engine was misfiring and running like a bag of whatever, the rev counter didn't show the problem.

Currently running with one from the distributor doctor, and had no problems since fitting that.

Graham

Graham this car has electronic ignition fitted

Ah, the condenser's not like to be a problem in this case then.

Mind you, others having the same issue and looking at the possible problems listed here might benefit.

Graham

GrahamFountain wrote: ↑Sat Mar 20, 2021 7:47 pm

mahony wrote: ↑Sat Mar 20, 2021 7:15 pm

GrahamFountain wrote: ↑Sat Mar 20, 2021 7:03 pm As well as the coil, might be worth considering the condenser breaking down when hot. I had a bit of trouble with newer replacement ones.

What I thought was odd was that when the engine was misfiring and running like a bag of whatever, the rev counter didn't show the problem.

Currently running with one from the distributor doctor, and had no problems since fitting that.

Graham

Graham this car has electronic ignition fitted

Ah, the condenser's not like to be a problem in this case then.

Mind you, others having the same issue and looking at the possible problems listed here might benefit.

Graham

Your breakdown symptoms point to fuel starvation to me. What about the fuel tank not venting? if and when it breaks down try undoing the filler cap. If there is an inrush of air and the car now start, the filler cap is not venting. The car will run until enough negative pressure is developed in the tank to stop the pump from sucking.

In 55 years motoring I have never had a coil fail - just saying.

As for the Distributor Doctor, he doesn't supply parts for the awful Delco dissy used on the 1850.

Bumpa wrote: ↑Sat Mar 20, 2021 8:04 pm Your breakdown symptoms point to fuel starvation to me. What about the fuel tank not venting? if and when it breaks down try undoing the filler cap. If there is an inrush of air and the car now start, the filler cap is not venting. The car will run until enough negative pressure is developed in the tank to stop the pump from sucking.

In 55 years motoring I have never had a coil fail - just saying.

As for the Distributor Doctor, he doesn't supply parts for the awful Delco dissy used on the 1850.

It's funny that and probably a coincidence but prior to breaking down I had just put £20 of petrol in.I will check the filler cap tomorrow I presume it should have a small hole in the cap?
Incidentally I have looked on "Autosparks" web site and they say a replacement coil has to be compatible with electronic ignition.Now I know that the coil was replaced by a previous owner because originally it was fitted with a ballast resister coil and now it isn't.
The suggestions on here will be checked out regarding the fuel starvation etc, but if that seems O.K I will replace the coil, and if that doesn't work I will replace the electronic ignition module as they are reasonably priced now.

Bumpa wrote: ↑Sat Mar 20, 2021 8:04 pm Your breakdown symptoms point to fuel starvation to me. What about the fuel tank not venting? if and when it breaks down try undoing the filler cap. If there is an inrush of air and the car now start, the filler cap is not venting. The car will run until enough negative pressure is developed in the tank to stop the pump from sucking.

In 55 years motoring I have never had a coil fail - just saying.

As for the Distributor Doctor, he doesn't supply parts for the awful Delco dissy used on the 1850.

Don't know about Dolomite, but with the TR7, the tank goes very flat and the car keeps running with no obvious problems - other than it's damned hard to get the cap off and it takes a bit less to fill the tank afterwards. That was with a US spec. unvented cap fitted, due to the counterman at the BL dealership having an off day. I got a new tank out of it though.

Graham

Then again, it was the mechanical pump that sucked the TR7 tank flat and I'm not so sure an electric one could.

Graham

I agree that it could be caused by having a non vented petrol cap fitted. Several years ago when it was very cold I had a similar problem and I my assumption is that I had ice form and block the vent path. When I took the cap off I could hear the air rushing into the tank and the engine started up once again.

I will attached a picture of a locking type cap stripped down so that you can see the vent path. There is no hole to see, there is a slot cut under the rubber seal and up the side. Very crafty. If you look carefully with the rubber seal in position you can see the slot up the side.