Poor warm starting.

[Clan]

Originally Posted by Laird Scooby

It's SOP for ANY petrol engine, particularly EFi where the mixture is usually arbitrarily enriched with the turn of the key to overcome either cold conditions (obviously cold engine) or to overcome fuel vapourisation (hot engine).
Very little wrong with the fuel pressure i would think, chances are the warm air intake valve has failed and is overheating the inlet manifold causing fuel vapourissation while stopped.

Note that fuel vapourisation will give a percieved reduced fuel pressure and many will accredit the fault to low fuel pressure, usually changing the FPR to no avail. The fact is the simple, obvious stuff is being overlooked and incorrect starting procedure being used.
To overcome this, many EFi systems have a bypass system fitted to increase fuel pressure when hot until the engine is started to overcome vapourisation.

With any fuel injection engine the correct start procedure is to just turn the key ... start procedures are programmed in either electronically or mechanically ..opening the throttle will upset these setting by letting too much air and/or giving more fuel than desired by the position of the throttle which is monitored.

[Clan]

Originally Posted by Laird Scooby

It's SOP for ANY petrol engine, particularly EFi where the mixture is usually arbitrarily enriched with the turn of the key to overcome either cold conditions (obviously cold engine) or to overcome fuel vapourisation (hot engine).
Very little wrong with the fuel pressure i would think, chances are the warm air intake valve has failed and is overheating the inlet manifold causing fuel vapourissation while stopped.

Note that fuel vapourisation will give a percieved reduced fuel pressure and many will accredit the fault to low fuel pressure, usually changing the FPR to no avail. The fact is the simple, obvious stuff is being overlooked and incorrect starting procedure being used.
To overcome this, many EFi systems have a bypass system fitted to increase fuel pressure when hot until the engine is started to overcome vapourisation.

All fuel injection systems have a rest pressure which must be held for at least 20 minutes, that is designed to prevent any fuel vaporisation because increased pressure raises the boiling point of any liquid . basic physics . .

I know of no fuel system which increases fuel pressure when hot , do you ?

Yes this case may well have fuel vaporisation that's why I asked that the fuel pressure be checked when the engine is turned off and watched for 20 minutes thereafter .

[heckflosse]

Originally Posted by 360beast

I very rarely disagree with you Dave but I can honestly say the last car I had to use throttle to start when hot was my 1984 carb 360, since then I've driven plenty of 7/900s and not one has needed anything to start when hot other than turning the key.

I think we may have overlooked something here... What fuel is it running? If it is E10 then you could very well have vapour issues thanks to the E10 boiling over at a much lower temperature than petrol. 7/900s have very hot engine bays when they're up to temperature.

The old Bentley's I worked on would have an overflow pipe for the carbs, if you had to road test them for a service and then drain the oil while hot you would often get ethanol dripping on you and that was on E5!

Sorry to hijack a thread, with a non volvo to boot, but we are having similar problems with our 3 litre Granada on hot days. Starts fine from cold but if you go shopping etc it will not restart. Usually have to lift the bonnet for a few mins. Sounds like modern fuel either vapourising or expanding and flooding the plugs?. Big cast iron engines stay hot for ages.
Had the same woes on my olds rocket too. Both run on normal unleaded not supergreen. Petrol isnt as we knew it.

[360beast]

Originally Posted by heckflosse

Sorry to hijack a thread, with a non volvo to boot, but we are having similar problems with our 3 litre Granada on hot days. Starts fine from cold but if you go shopping etc it will not restart. Usually have to lift the bonnet for a few mins. Sounds like modern fuel either vapourising or expanding and flooding the plugs?. Big cast iron engines stay hot for ages.
Had the same woes on my olds rocket too. Both run on normal unleaded not supergreen. Petrol isnt as we knew it.

Try using Esso 99 as they state on their website that even though it says E5 on the label it contains no ethanol. My 940 loves it and runs better on Esso 99 than anything else.

[Clan]

Originally Posted by heckflosse

Sorry to hijack a thread, with a non volvo to boot, but we are having similar problems with our 3 litre Granada on hot days. Starts fine from cold but if you go shopping etc it will not restart. Usually have to lift the bonnet for a few mins. Sounds like modern fuel either vapourising or expanding and flooding the plugs?. Big cast iron engines stay hot for ages.
Had the same woes on my olds rocket too. Both run on normal unleaded not supergreen. Petrol isnt as we knew it.

Is yours carburettor or fuel injection?

[heckflosse]

Weber carb. It sits on a plastic heat sink spacer and the pump is mechanical.

[griston64]

Originally Posted by 360beast

Try using Esso 99 as they state on their website that even though it says E5 on the label it contains no ethanol. My 940 loves it and runs better on Esso 99 than anything else.

My Turbo seems to run really well on Esso 99 as well. Much better than on BP or Shell

[Laird Scooby]

Originally Posted by 360beast

I think we may have overlooked something here... What fuel is it running? If it is E10 then you could very well have vapour issues thanks to the E10 boiling over at a much lower temperature than petrol. 7/900s have very hot engine bays when they're up to temperature.

The old Bentley's I worked on would have an overflow pipe for the carbs, if you had to road test them for a service and then drain the oil while hot you would often get ethanol dripping on you and that was on E5!

Good point about the E5/E10 fuel Luke! Could be contributory!

Originally Posted by Clan

I know of no fuel system which increases fuel pressure when hot , do you ?

Yes - Honda PGM-Fi which opens a solenoid valve to atmosphere on the FPR to give maximum pressure on a hot start, closes it again as soon as the engine is running. It's set up to do it above certain temperatures only.

Originally Posted by heckflosse

Sorry to hijack a thread, with a non volvo to boot, but we are having similar problems with our 3 litre Granada on hot days. Starts fine from cold but if you go shopping etc it will not restart. Usually have to lift the bonnet for a few mins. Sounds like modern fuel either vapourising or expanding and flooding the plugs?. Big cast iron engines stay hot for ages.
Had the same woes on my olds rocket too. Both run on normal unleaded not supergreen. Petrol isnt as we knew it.

Very common problem with those downdraught Webers, Southern Carburettors and similar carb specialists can supply a thermal gasket which will relieve some of the symptoms of heat-rise which is almost certainly the cause of the problem.

http://www.southerncarbs.co.uk/onlin...cessories.html

Couldn't find the thermal gasket so if you contact them, they should be able to help with your 38DGAS carb. Alternatively i just remembered these people and here's the item that is most likely to help :

https://www.burtonpower.com/carb-bas...nto-fv766.html


Also check your air cleaner inlet, certain Fords had a snout on them that could be rotated for winter and summer to inhale warm or cold air respectively. Usually it pointed downwards over the exhaust manifold for the hot air in winter position and faced forwards for summer.

Definitely worth running on 98 octane unleaded, the Essex wasn't really built for anything less than 4 star which is what 98 Super Unleaded replaces.

[Clan]

Originally Posted by heckflosse

Weber carb. It sits on a plastic heat sink spacer and the pump is mechanical.

That was a problem in the 1980s as well so not fuel .. The volvo 440 with a twin choke downdraught carburettor has a small fan which blew air over the carb for about half an hour when you turned it off to prevent that problem .

[heckflosse]

Thats right, i remember them.
Thanks for the replies chaps, I will check out Burtons anyway.
Spirit of Barry Lee and all that. You can get back to Volvos now!
Cheers, Jim