Help! Fuel issue 1976 SL 350

[Lee alex]

Hi guys!!
She’s an old girl with a few fuel issues.
I’m a no professonal when it comes to these cars but I know my way around a spanner. I picked the car up today & it has a starting issue, I have researched the most common issues with this models being, fuel pump which primed up & can hear running, fuel distubtor took all the pipes off and fuel is running through every one of them nicely. Only thing I can’t see is if the fuel is running to the injectors is the injectors a common issue to seeze up given it being sat around for a while? I’m getting a good spark so there’s no issues there. Any pointers or help would be appreciated

 

[robparker]

Injectors can seize if sat for a long time, but are easily bench-tested to see. Luckily you have k-jet so injectors are very cheap.
What is the starting issue though? Cranks and never starts, splutters into life??

 

[Lee alex]

How would you suggest checking the injectors? Yeah it turns over no problem at all but just doesn’t fire!

 

[LostKiwi]

If you fire a squirt of ezi-start down the inlet does it fire?

 

[Lee alex]

If you fire a squirt of ezi-start down the inlet does it fire?

It’ll fire if I pour fuel into it!

 

[LostKiwi]

Ok so definitely look at the injectors.

 

[robparker]

How would you suggest checking the injectors? Yeah it turns over no problem at all but just doesn’t fire!

You will need to remove them and use a tester which will built up pressure to and beyond the point at which they should fire. Plenty of YouTube vids available.

 

[Lee alex]

Hi guys, just an update, I don’t believe fuel is coming out of the injectors. I have flushed the injectors out with a home made bench test and under a good bit of pressure they mist up quite nicely. Once back on they don’t mist up under the pressure the cars producing. Is this down to a fuel regulator or am I missing something. Thanks.

 

[Tashman]

Does it hold good fuel pressure when its parked up or does the pressure drop away. Could be accumulator?

 

[robparker]

Accumulator will make (hot) starting difficult but not impossible, so unlikely. Have you measured fuel pressure whilst cranking?

 

[Lee alex]

Another update, turns out the fuel pump relay is dodgy i bypassed the relay my connecting a separate battery to the fuel pump & it started & ran lumpy & back fired one of our local mechanic told us we must have the ignition leads on wrong somewhere hence the misfire, we searched high & low for the timing order annoyingly the Haynes manual says nothing another local mechanic looked at it and got the timing order right & it’s back to square one again even with the fuel pump running it’s not firing, he have checked all the spark plugs & all the injectors they all work as they should. Any more suggestions before I buy all new leads & injectors. This car is making me loose my marbles!!

ThAnks guys

 

[DREAMER NO2]

Lee will this help ?

 

[LostKiwi]

So hang on....
With a plug in the wrong place it ran poorly but did run? Then you corrected it and it no longer runs? I'd be re-checking the firing order again.

 

[DREAMER NO2]

If its been standing the fuel is suspect as well. Go through the fuse box and clean all the fuses up on the ends..
When you get it running put some REDX in the tank it will help to clean out the injectors ..To clean them on the bench you will have to back flush them .. Do a fuel presure test .

 

[Lee alex]

I’m going to have to check it again how would I find the top dead centre on this engine?

Thanks

 

[LostKiwi]

The only proper way to do it is to remove the rocket cover for number 6.
Turn the engine over until number 6 exhaust is closed (or nearly closed) and number 6 inlet is just opening. Then with a screwdriver down the plug hole (number 1 or 6 as both will be top of their stroke) feel for the top most movement of the piston.
That is the position number one will be looking to fire at.
At that point the rotor arm should be pointing to number one cylinder. If not the distributor has at some point been removed and not reinserted in the factory position (not sure if this is possible on this engine but it is on other engines). It doesn't particularly matter if its not but it might explain a few things!

Here's another diagram showing firing order and how the leads should fit.

If you just feel for when the piston is at the top for number 1 (or 6) cylinder without checking the valves you can get the timing 180 degrees out which will cause the engine not to start

 

[Lee alex]

That’s lostkiwi,

Yet another disaster today. Got the timing spot on but it still wasn’t firing... pulled & injector out again and no fuel. Even with a 12v constant live to the fuel pump, there is fuel coming to the injectors but not enough pressure to come through. I am a loose end with this car now. I have had the nipples off the fuel distributor and the fuel is coming up evenily via all of them. There is good pressure via the cold start injector but yet that’s not spraying either.

 

[Lee alex]

I have also nothing coming from the return

 

[robparker]

Where are you?

 

[Lee alex]

Hertfordshire