no warm start

[silverfox]

I have a mint merc300s with the 103 engine. Starts every time when cold and most times when warm,But occasionaly it wont start when hot. Leave it for a while approx 30 mins and starts ok. I have replaced fuel pump relay-vop-roter cap and leads- thermal switch in the cyl head-spark plugs. I have tried everything. Any help would be appreciated. It is a 126 model 1990 with 99000 miles.

 

[jsl]

I have a mint merc300s with the 103 engine. Starts every time when cold and most times when warm,But occasionaly it wont start when hot. Leave it for a while approx 30 mins and starts ok. I have replaced fuel pump relay-vop-roter cap and leads- thermal switch in the cyl head-spark plugs. I have tried everything. Any help would be appreciated. It is a 126 model 1990 with 99000 miles.

Has it got an alarm system? Had this on mine and it was the isolator swich of the alarm system contacting when engine compartment was warm.

 

[gaz_l]

Without wishing to be the bearer of bad tidings, the last time I had a car with those symptoms it was due to a failed head gasket. Better get that checked out...

Cheers,

Gaz

 

[silverfox]

Has it got an alarm system? Had this on mine and it was the isolator swich of the alarm system contacting when engine compartment was warm.

Thanks for reply--car doesnt have alarm system

 

[Dieselman]

Low fuel pressure causing vapour lock in the injection system.

 

[silverfox]

Without wishing to be the bearer of bad tidings, the last time I had a car with those symptoms it was due to a failed head gasket. Better get that checked out...

Cheers,

Thanks for reply-- checked my compressions with compression gauge--reads 150 psi plus or minus 5%. when hot---I needs look elsewhere -- Steve.

 

[silverfox]

Low fuel pressure causing vapour lock in the injection system.

thnks for reply--havent tried this --will do asap---steve

 

[kth286]

I was also thinking fuel pressure not staying up.

Could be problem with fuel accumulator (near fuel pump) and/or fuel pressure regulator (diaphragm split).

 

[grober]

As kth286 fuel pressure regulator AKA the Warm Up Regulator -normally bolted to the front end of the cylinder head. Alternatively- ignition failure due to overheating of the EZL ignition unit bolted to the wing ( heat sink compound between it and the inner wing dries out allowing it to overheat).

 

[silverfox]

Thanks for the info Grober andkth29, I will investigate asap and post back my results. Everyone seems very helpfull on this forum. Steve