I put a new 10000km engine in my xj series 3. Over Christmas I drove 4000km. Everything is perfect except cannot count on it starting hot. It seem to be fuel/ air mixture as throttle sometimes helps. Motors over well. Strong battery. Never stalls and once going is perfect. Water temp sits just above 90. Always starts well cold. Last engine did not do this. Sometimes starts hot but it doesn't jump to life like it does cold

 

Just been reading old posts of Aussie_series3. He had the same symptoms with leaking induction gasket. I am using coolant. 1/2 L over 2000 km. Why are there coolant galleries under the induction gasket?

 

4.2 fuel injected, 5.3 fuel injected, or 3.4 on carbs?

If a v12 there inlet manifolds are dry.

If a six cylinder (at least the 4.2) the inlet manifold is dry but the gasket might be a block-off for a coolant passage that is used in a different/earlier application. For the life of me I can't remember at the moment....maybe cuz I'm only had three sips of coffee.

Probably the same for the 3.4 as well.

Cheers
DD

 

Hi guys... What if it's just vapor locking? I know the cooling bypass for the gas line on my '75 Jag with a 4.2L carbureted would cause a major vapor locking issue. I could get my Jag to start with quarter throttle and cranking for 5 seconds. If you haven't tried to, just connect your gas line directly from where it comes into the firewall to the T pipe going into the carbs (if that's the case).

 

Vapor lock/fuel percolation is certainly a possibility. The FI models have a fuel cooler...not sure about the 3.4 models running on carbs.

Also, the FI models (after '81 or so) had a fuel temp switch on the fuel rail which gave increased fuel pressure at xxx-fuel temp to help prevent hot start issues

Lots of 'could be' items to discuss but it would be a shorter list if we knew the year, engine, etc


Cheers
DD

 

Sorry guys,it's a 82 series 3, 4.2 injected.When we put the engine in that had been siting for 10 years we did not touch the induction gasket. Water temp does run slightly higher than 90 c. Will post temp today. What water temp is too high? Will question Aussie_series 3 about his problem.

 

Slightly higher than 90ºC is no problem.

Your 4.2 has the CEI--Constant Energy Ignition. Both the coil and the ignition module are known to give problems once they've absorbed a bit of engine heat. Be ready to check for spark next time the hard start/no start happens. Not only do you want spark, of course, but you want a nice bright blue spark....not a wimpy orange/yellow spark.

Sometimes a fuel pump will give trouble only after running for a bit....although this obviously wouldn't be related to engine temp. Next time this happens put the gearshift in "D" and turn the key to "Start". You should hear the fuel pump humming away. If not, post back.

Another trick to try next time: remove the plug to the coolant temp sensor (the one foe the fuel injection) and jump the terminals with a paper clip....then try starting the car. Any change?

By the way...when the engine does eventually fire up do you get a puff of black smoke from the pipes? If so, that's an important clue

Cheers
DD

 

The engine runs at 100 degree c. Is this too hot

 

Running at 90 would be nicer but might not be possible. It might be that your cooling system simply doesn't have the capability of holding 90.

Running at 100 is not too hot if it holds there and doesn't keep climbing up-up-up. Not to worry.

My Ser III 4.2 would hold 90ºC until ambient temps hit 32ºC or so. After that the system struggled to hold 90ºC and would creep up to 100 or so....especially in traffic.

However, if you are running 100ºC when ambient conditions are mild....say 20-24ºC or less, then you should investigate for a problem.



Boil over point with a 16 psi cap at sea level is about 126ºC...not that you wanna get anywhere near THAT hot with aluminum heads and elderly head gaskets !

Cheers
DD

 

Thanks Doug . I removed the air inlet pipe to throttle body last night. Inside the manifold was a small pool of black looking fluid that I absorbed with a rag. Could not tell what it was. Best description was gun oil. Thin viscosity with pungent smell. I assume concentrated fuel dye with fuel. Is it normal that there would be a pool of it. My fuel rail had a loose hose from the vapour purge valve. How does this valve work? One hose goes to vacuum and the other to the valve. When I removed the hose with engine running at the valve it spat out fuel? Fuel pump working in drive and no black smoke on cold start up. Cap mod not fitted. I am in the Northern Territory of Australia. Temp is usually 30 -40 degree c

 

Finally got to the bottom of the problem. The fuel pressure regulator was regulating properly but had a hole through the diaphragm which is tapped into the intake manifold,thus making the mixture very rich which was fine when cold. No good for hot. Runs beautifully now and starts well all the time