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740 Fuel leaking from Exhaust Manifold

S

Supersneak

New member
Joined
Oct 4, 2017
Location
Oregon
I recently did a head gasket job on my 88' 740 Turbo, Had the head machined, had to remove cam to take it into the shop but all valve shims were within spec so they all went back in. Got the engine back together and into the Volv. Car wont start, i can get it to start up real quick on starter fluid, but i have a pretty substantial amount of fuel leaking out of the exhaust manifold. absolutely no idea what could be going on.

Edit: Tested injectors and none seem to be stuck open, they're fairly new and don't have more than 50 miles on them
 
I assume it ran ok before the HG job?

I’d start by making sure that the engine is mechanically timed correctly, in other words that all timing marks line up correctly.

Also make sure that no electrical connectors got swapped on reassembly. Some of them can be interchanged if you’re not careful.
 
It was overheating before the head gasket job but other than that, it was totally sound. No valve job was done, they did a compression test and it was all good.
 
Gas tank over full. :-P

If none of the injectors are leaking, how did you check?

Is the fuel pressure regulator leaking fuel into the intake?

Something has shorted one or more injectors causing them to open electrically (uncontrolled).

A Battery charger on boost and a dead battery can cause this too.

First before attempting to start.

Eliminate the excess fuel (get your nomex undies out)

ROtate the motor a couple of turns backwards so you are sure it will not hydraulic.

The less safe version is, to pull the plugs and trigger the starter to clear the motor without turning on fuel and ignition. (Nomex undies and outside near a hose for you and a fire bottle or two for the car)

Then fix the problem test and be sure fuel not being dumped.

If you have a muffler full something should be done to clear it (drill a drain hole?)

Before starting CHANGE THE OIL.
 
Pulled the fuel rail and turned the engine over. Had a camera on the injectors and they seem to be putting out alot of fuel. And they stay on for a few seconds after the ignition is off. I am the only person at my shop currently so I can't get a super accurate idea if the spray pattern is normal but all 4 injectors seemed to be over spraying
 
Last edited:
Yeah I dropped a new distributor into it, it's the in block distributor with the hall sensor on the bottom. Where exactly was your sensor messed up on the wire
 
I was having some troubles initially with the starter after the rebuild, had to replace it. what could be causing the injectors to stick open electrically?
 
So my injectors were on warranty so I swapped them out just to be sure. They are still shooting alot of fuel, what could be causing the injectors to stay open electrically?
 
VB242 said:
Bad ecu
Click to expand...

So that's the way it's headed. I plugged a noid light into each injector and it's very much the same story as the fuel spraying pattern. Noid light comes on when the key is in the 2 position. And throughout cranking the engine, doesn't pulse. Before we go to ECU what else could be causing the constant power
 
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