1800S Intermittent Fault

[LHarrison]

Hi everyone

I am a new member to the forum and would like some assistance if possible please in relation to a problem that I am having with my 1969 Volvo 1800S. This is an intermittent problem, unfortunately, but when it does occur it happens within the first mile of travel and after that it seems to clear completely. The problem is that the engine pulls as if it is going to stop and today I did have to pull over and stop the car as the pulling was so bad, however, the engine did not stop completely but ran very unevenly with the revs going up and down. When applying the accelerator it immediately stopped. After one minute I started the engine again and all was well and the car drove perfectly from then on. I have already had the twin carbs checked and balanced, the timing checked and the plugs changed. So if anyone has had a similar problem or can offer any advice it would be very much appreciated.

Thanks

Laurie

[Ron Kwas]

Laurie;

Welcome to this forum!

We will need some more specifics in order to help..."within the first mile of travel" is only a part of what we need...is this immediately after Start-up, while still choked and before engine is warmed up?

What kind of "twin carbs" (SU-HS or HIF or Zenith-Stromberg) both later have some thermal provisions...

Please elaborate on "pulling"!

Cheers from Connecticut!

[CLIVERALLY]

Do you mean hesitating? If it was working fine before then .. If so check for dirt in the fuel lines and clean the carb bowls out and change if fitted inline filter. You say you have had the carbs balanced, take off the air cleaners and make sure the pistons are free and returning start the car and check they raise at about the same time when throttle is opened. If you did not do carbs yourself stand back and look at them....are the idle screws still there or has one fallen out ( even tho they are spring loaded I have seen this happen) If all OK on the fuel front then other things to check are the coil ,plugs and if you still have them points and condensor .

[LHarrison]

Originally Posted by Ron Kwas

Laurie;

Welcome to this forum!

We will need some more specifics in order to help..."within the first mile of travel" is only a part of what we need...is this immediately after Start-up, while still choked and before engine is warmed up?

What kind of "twin carbs" (SU-HS or HIF or Zenith-Stromberg) both later have some thermal provisions...

Please elaborate on "pulling"!

Cheers from Connecticut!

Hi Ron

Thanks for the response. Yes it is after start up and once the problem has occurred it will not happen again even if you stop the car, leave it for a while and then start it up again. It seems to only occur following the first cold start and within a few minutes of start up at least up until now anyway. The choke is still out but not a lot. Just for information when it happened last and I had to pull over, I tried pulling the choke out a little to see if it would steady the revs but it didn't.

According to the car instruction book the carburettors are Zenith-Stromberg 175 CD 2SE's.

Pulling means that the car jerks as if it is going to stop and it judders shaking you backwards and forwards a bit in the drivers seat. I have had this before in older petrol driven cars and it is usually a precurser to the engine cutting out and the car drifting to a halt. The only difference here is that up until now it has cleared after a few seconds and the car has remained moving. The last time it was so bad, however, I had to bring the car to a halt at the side of the road.

Hope that helps and thanks again for replying.

Laurie

[LHarrison]

Originally Posted by CLIVERALLY

Do you mean hesitating? If it was working fine before then .. If so check for dirt in the fuel lines and clean the carb bowls out and change if fitted inline filter. You say you have had the carbs balanced, take off the air cleaners and make sure the pistons are free and returning start the car and check they raise at about the same time when throttle is opened. If you did not do carbs yourself stand back and look at them....are the idle screws still there or has one fallen out ( even tho they are spring loaded I have seen this happen) If all OK on the fuel front then other things to check are the coil ,plugs and if you still have them points and condensor .

Hi Clive

Thanks for the response and the PM which has been noted.

Just a few comments on what you suggested. I would not use the word hesitating here, this was a strong pull as if the car was going to stop, it would then jerk forward and then pull back again. Much more than hesitation.

The problem I firmly believed was something to do with the carbs and so I had an engineer who is used to working on classics come and check them over. He did clean out the bowls and check the pistons. He also checked the choke cables and did the balancing. I will as you suggest, however, check the idle screws. As regards the fuel, I was certainly thinking of changing the fuel filter but it does seem odd that up until now it has been a cold start problem. If the fuel was contaminated I would have thought that the problem would have been more random occurring at any time rather than on the first cold start. Just to add that after the car started again on the last occasion, I took it to a local stretch of dual carriageway and it was doing 60 mph plus with no problems at all. I then took it out to the same place later that day, after the engine had been switched off for some hours, and there was no problem at all and again it was doing the same high speed.

I have not checked the electrics yet and I will have to do so but I must admit that from my limited knowledge of older cars, this does seem to be more of a fuel issue than an electrical one but I may be proved wrong.

I will check out a few of your suggestions and see how things go.

Thanks again for responding.

Laurie

[arcturus]

Does it feel as though it's briefly running on three?

[arcturus]

Have you checked your dizy cap for internal hairline cracks. Try spraying inside the cap with some WD40 before you start it up to expel any moisture. if you have hairline cracks they could hold moisture which would cause tracking and misfiring. moisture would dry up with the heat after a short running period and the car would run normally.

[LHarrison]

Originally Posted by arcturus

Have you checked your dizy cap for internal hairline cracks. Try spraying inside the cap with some WD40 before you start it up to expel any moisture. if you have hairline cracks they could hold moisture which would cause tracking and misfiring. moisture would dry up with the heat after a short running period and the car would run normally.

Thanks Arcturus I will give the WD40 a try. No not running on 3 more like it wants to stop then start again then stop it is a jerkiness that you feel.

Laurie

[CLIVERALLY]

Get yourself a Stromberg manual ...it will pay a dividend.
I have one if you are struggling...used to work on twin Stromberg Firenzas

[LHarrison]

Originally Posted by CLIVERALLY

Get yourself a Stromberg manual ...it will pay a dividend.
I have one if you are struggling...used to work on twin Stromberg Firenzas

Thanks Clive I will keep my eyes open for one.

Laurie