420 SEC Won't start

[Noidea]

Hi

I have recently purchased a 1988 420SEC on a whim. It came on a trailer without a drop of petrol in the tank, it had been stood for two years. I put some fuel in the tank and connected some jump leads, it started straight away! It ran for about 3 minutes than cut out. Now it won't start at all. I have order a new battery, but I think its a fuel related issue. Any suggestion, I have no idea about engines this is my first project - midlife crisis possibly?

Thanks

Noidea

 

[stwat]

Hello and welcome.

Can you hear the fuel pumps prime when you switch the ignition on?
Check the fuel pump relay by removing it and cleaning the contacts. Simply removing and replacing it may fix the problem.

The relay is number 137 in this diagram.

 

[martyz]

A good couple of gallons will be a good starting point,fully charged or new battery and I reckon it will run again.

 

[ianrandom]

Silt in the fuel pumps perhaps? It only takes a little dirt to upset them apparently.

I wonder if you'll need to change the tank. Bit silly of the previous owner to leave it empty. If so, try Rob Parker at Three Pointed Parts, a secondhand tank wont cost too much.

 

[grober]

You also have to ask why it stood for 2 years? There may be a pre-existing fault which put it off the road in the first place? Could be the fuel pump/FPR-- could be the EZL ignition unit -could be a blocked fuel filter Could be condensation in the distributor cap- water in the base of the distributor volatilises with engine heat and deposits on the underside of the cap [ which was initially dry] causing an HT short. Try drying out the distributor CAP+ Body with a hair drier. Check the state of the plugs- can explain a lot e.g wet-excess fuel= prob an ignition failure ----- signs of running hot= weak mixture inlet manifold leaks etc etc.

 

[jaymanek]

most likely the fuel relay...

Can you hear the buzzing of a priming fuel pump from the back of the car when you put the ignition on?

 

[Noidea]

Thanks all, I'll be needing a lot of help with this. There is a buzzing noise come from the rear of the car when I turn the ignition on? Any suggestion Jaymanek?

 

[grober]

Can still be the fuel pump relay as JAY says . Its 2 stage --- first "priming stage" seems to be working but then it should switch to the second state "continuous supply" when it gets a signal the engine is running. this is a safety feature to stop the pump flooding the engine compartment in the event of a crash damaging fuel lines. Could still be the fuel pump relay or its not getting the engine running signal.

 

[jaymanek]

The best test for that is to jump two pins on the fuel pump relay by wrapping some wire around them.. so pull up the fuel pump relay located on the right hand side bulk head... Off the top of my head its pins 30&87 or maybe 15&87? Two pins directly opposite each other...
Wrap some wire around them, plug it back in and the fuel pump should run continuously...

Obviously once you have tested then remove the jumper wire...

I will check the pin numbers later and come back to you.

 

[dinoy]

kickdown relay i have some for v8 should work around £50 delivered

 

[Noidea]

She's running well. Thanks all. now the brakes are sticking? See new thread

 

[jaymanek]

so what was it.

 

[Noidea]

so what was it.

The relay pins. Thanks

 

[Noidea]

W125 420 sec

Hi

I'm still have problems with the fuel I think. She turns over lovely and ticks over for about two minutes at about 1000 rev, then slow fade to 500 then stalls.

I have fitted a new fuel filter, oil filter, air filter, new plugs, new oil and coolant. The fuel pumps seem to be pumping fuel?

Does this car have a CAT convert? Does unleaded petrol effect the running, its a 1988 SEC, should I add a lead replacement? Could it be the air flow meter, fuel pumps or Fuel pump relay?

Any idea's to keep her running would be greatly received.

Thank, NOIDEA

 

[grober]

What you describe is the normal warm up phase which uses a richer mixture and an increased throttle bypass to keep the revs up. The fast idle throttle bypass may be faulty or the mixture when warmed up is weak [ possible inlet manifold or associated pipework leaks]. You really need to get the car on an old fashioned engine analyser with someone familiar with these cars to check the ignition firing line and the exhaust gas levels at idle. you would be guessing otherwise- its money well spent imho.