Howdy all, I'm new to this place.

I recently purchased this beaut with 360k miles on it. It is a non-turbo GLE with a turbo engine installed and the turbocharger removed... So not sure how to call it. Anyways I recently moved to the mountains of Colorado where the air is cold and thin, and this started happening:

I go to start the car, cranks fine but does not start. While troubleshooting the fuel system, I pull the fuel line from the fuel rail and stick it in a bottle, and crank the car... and suddenly it starts. With no continuous fuel source, the engine runs for 5-10 seconds, then dies. About 10oz of fuel end up in the bottle. When I reconnect the fuel line and crank, the car starts fine, and carries me the 45 minute drive to work. Next time I go to start it, same problem. So I go through the disconnect-start-reconnect-start procedure, and off I go.

Next time I fuel up, I go to a higher octane fuel (from 86 to 88), and add a bottle of fuel injector cleaner, and the problem goes away... until recently, as the tank has gotten around 1/2 empty, and it's become increasingly common. In fact, twice I have lost power while driving, once temporarily and once the car actually died, and I went through the disconnect-start-reconnect-start procedure, and again... fine.

I have a theory but I'd like to hear yours first. So --- whaddaya tink??

 

the turbo engine has much lower compression than the normal engine, the turbo makes up the difference.

so which EFI and ignition system is on this hybrid ?

which fuel line is that you pulled? the line from the fuel pump to the fuel rail, there's no way the engine can run without fuel pressure provided by that fuel pump, these aren't carbereuters, they need 42PSI pressure to squirt gas.

if it was the /return/ line, then sure, its a closed loop, gas is pumped from the fuel pump to the fuel rail, past the injectors, into the fuel pressure regulator, and excess gas (thats almost all of it) returns to the fuel tank via that return line.

 

I'm not sure how to answer your first question. I believe it has LH Jetronic, but not sure what other types of systems are available. Hate to contradict you, but I did indeed pull the line from the fuel pump to the fuel rail, not the return line, and the engine started and ran for 5-10 seconds.

 

when you turned on the key, several ounces of fuel should have spurted out of fuel line as the fuel pump primes, and when you cranked the engine, quite a lot of fuel should have gushed out of that fuel line until the engine stopped turning over. there would have been zero pressure on the fuel injector rails, hence zero injection.

is the car using the original injection and ignition control units, so you just swapped the block? then its LH 2.2, where the injection and ignition timing comes from a hall sensor in the distributor (1989+ non-turbos and 1990+ turbos use LH 2.4, where the timing comes from a crankshaft position sensor).

btw, did you swap the injectors back to your non-turbo injectors, or are you using the turbo injectors that came with the turbo block? turbo injectors require a series ballast resistor or they'll fry the output of the ECU, this resistor pack is mounted on the left fender wall just behind the headlight and near the battery on the turbo car.

 

The previous owner says the top end, intake, and exhaust are different. I haven't done any of the work on this car so far besides replacing the brakes. This is my first Volvo and second car so I'm unfamiliar with a lot of this terminology, sorry. I can tell you, though, that I've driven the car 3k miles without a problem until now. I guess I'll spill my theory now: could it be the fuel pressure regulator?

 

The previous owner says the top end, intake, and exhaust are different. I haven't done any of the work on this car so far besides replacing the brakes. This is my first Volvo and second car so I'm unfamiliar with a lot of this terminology, sorry. I can tell you, though, that I've driven the car 3k miles without a problem until now. I guess I'll spill my theory now: could it be the fuel pressure regulator?

 

your first statement, 'top, intake, exhaust are different', do you mean, they used the head, intake and exhaust manifold from the non-turbo car, mated with the lower block from the donor turbo engine ? if so, then you're probably using the non-turbo car's injectors, so my ballast resistor thing doesn't apply.

the fuel pressure regulator is on the output/return side of the fuel injector pipe. it 'blocks' the returning fuel until its at the required pressure of 42-44 PSI (for turbo and later engines, early non-turbo used ~ 38 PSI), any fuel in excess of this pressure passes through the FPR and returns to the fuel tank. Its slightly more complex than this, the FPR is also connected to intake manifold vacuum (skinny hose into back of FPR), and the actual absolute fuel pressure is relative to manifold vacuum (so if nominal pressure is 42 PSI, and the manifold vacuum is -7 PSI (typical at idle with the throttle closed), the actual pressure is 42-7 = 35 PSI).

you test the fuel pressure regulator with a fuel pressure gauge, this is installed via a T on the incoming fuel line at the other end of the rail, or via the schaeder valve, if present, then you start the fuel pumps and measure the pressure.

 

Also, it seems like you're saying that what happened with the fuel line could not happen, but it happened... Promise. The car started and ran for a few seconds with the line disconnected from the fuel rail.

 

Okay. I went down to the friendly local auto parts store to borrow a pressure tester but they did not have the right fittings. So I have to attempt a blind repair. In your opinion, could the fpr be the problem?

 

WAY too many variables here, I'm not going to hazard a guess. USUALLY, when a fuel pressure regulator fails, gas will be dribbling or spurting out the vacuum fitting (eg, disconnect the vacuum hose, crank car briefly while checking for squirting gas from said fitting).

running for 10-15 seconds is different than running for 1-2 seconds. its concievable if its been flooding from too much fuel, that with the fuel disconnected it could run for 1-2 seconds on the accumulated vapor in the intake manifolds, but highly unlikely it could idle for 10-15 seconds.

another test... everything hooked up normally, crank the car for 10-15 seconds, then pull a spark plug as quickly as practical, and inspect the plug end to see if its wet with gasoline. this indicates its getting gas, possibly too much gas.

 

I timed it, and it runs for seven seconds with the fuel line disconnected. I think the problem occurring ONLY when under half a tank of gas is in the car is a hint here. I remember reading something about it earlier but can't remember where. The FPR doesn't appear to be leaking, as the vacuum fitting is dry. Don't have the right spark plug socket size so that will have to wait.

 

Still stumped here. Any ideas? Just to recap:

Above half tank of gas, starts and drives fine.
Below half tank of gas, occasional no start, requiring following procedure -
1. Disconnect fuel line from fuel rail
2. Turn key, car starts, runs ~7 seconds, dies
3. Reconnect fuel line to fuel rail
4. Start car, no problems until car sits for a while.

 

i'm gonna guess messed up in-tank fuel pump.

 

Fuel System: Pumps, Relays

I'm inclined to agree! Thanks for the tip.

So I just went out to the car to do a lil diagnosis. The tank is about 1/4 full so I used the 'alternative method' to start, and then while it was idling I pulled fuse 11, disabling the in-tank pump. There was no difference in the performance of the engine, but I thought I could hear an irregular buzzing sort of sound from the front right (???) when the fuse was removed. This doesn't make sense to me, unless the buzzing was unrelated/imagined, and the in-tank pump is non-functional.

Curve ball: after this test I was messing with the vacuum line to the fuel pressure regulator, and capping the line from the manifold with my thumb a few times while revving the engine up and down. I was trying to see if the FPR being attached made any difference in the engine performance, which it did not. UNTIL, all of a sudden, the engine sound changed totally, becoming less 'throaty' and more 'tinny,' and stayed that way no matter what I did with the vacuum line. After a little inspection to make sure nothing catastrophic happened, I drove down the street and back and the car drove just fine...

I may be out of my depth here. My only guess is that the problem is a combination between the FPR and the in-tank pump, and by momentarily capping the vacuum line I broke some sort of clog? I dunno...

 

the fuel pressure regulator keeps the pressure in the fuel rail at about 43 PSI minus the manifold vacuum. at idle, the vacuum is like -7psi or something, so the pressure is dropped to 42-7 = 36 PSI. The ECU assumes this when it sets the fuel pulse duration.

if the vacuum hose is disconnected, or leaky, the fuel pressure at low throttle settings will be higher than expected, resulting in too much fuel, and a rich running engine.