S2 Stag Not Firing :(

[DaveB]

Well car has been a bit difficult to start for the first few days after getting it back, spent a month roughly all up at the workshop getting the engine rebuilt.

Fuel pump is less than 12 months old (actually I think it's closer to 6) and was installed by the same workshop new (Walbro GSS-342, the 500hp in-tank job).

I suspect the fuel pump because the car cranks fine, just won't fire. When I turn just the ignition on (not cranking) I hear a strange noise like a "chug... chug... chug... chug... <then silence>" from the boot/fuel tank area. It sounds like the pump's trying to crank over and can't.

1/4 tank of fuel; new fuel filter at compliance (about 40,000 K's ago), new fuel sock with fuel pump.

Measured 12.5 volts or so at ignition at the pump connection.

Anyone else had a similar experience with their stag at similar K's (~134,000)? Especially with this model pump?

Not bagging the pump... I'm actually going to replace it with another Walbro (same model - I bought a bosch 040 but it's massive by comparison and I don't have the inclination to hack up my cradle for what is really a vertical-mount pump).

[pyro-ns]

disconnect fuel hose @ the filter, have a good rag handy, turn the key to ignition (ie, don't start it) and the pump should prime and pressurise the line. check the relay also. see if you can swap it with someone else, or at least swap it with something else in there first. check any other fuses too.

[DaveB]

Thanks, checked fuses/connections, verified power at the pump. I should have mentioned, no pressure... can squeeze & bend hoses. Can't feel pulsing. Plus it fired once before it died, and has not given a single puff since.

[pyro-ns]

next step is to remove pump and inspect then i guess. it's a bit hard for the foot to get clogged, but anything's possible. see what kind of warranty you've got on the pump, or if you can work something out with the workshop if you suspect foul play.

else, change brands i guess?

best of luck either way

[DaveB]

Thanks Josh. Yeah, I can see what you mean about the foot being difficult to clog; it certainly doesn't look clogged. I'd like to dry-test the pump but I'm not sure if that's good for it, and it's still full of petrol(!) - shake and more comes out...

There doesn't appear to be much dirt around; I see a bit in the bottom of the tank, and some metallic-looking specks around the place too (I heard this can be the insides of the fuel pump, and / or its brushes). I did fish a piece of sealant out of the tank and a clamp which was floating.

I think the Bosch pump would have to be more reliable and higher performance, considering the massive difference in size/weight, but I would really have to hack up my cradle to fit it, and I don't know how well the thing is supposed to be encapsulated in the cradle etc. to ensure I don't get fuel starvation problems. So I may just have to go for another Walbro... and I think a new fuel filter.

[KiwiRS4T]

Could be a blockage somewhere. Have you replaced your fuel filter (in the engine bay)? You could test the flow by pulling the hose off the rail and measuring what comes out when you turn the key (need a stop watch or just the second hand on your watch and a container of known capacity to measure fluid e.g. the Walbro is rated at 255l/hr or 4.25L/min so

15sec should del just over a litre (1.06 l)

or 12 sec 0.85 L

or you can test the pump out of the car if you want to pull it out. Just stick the pickup in a container of petrol attach a 12v supply and measure the flow for a minute or 30 seconds or should fill a 2L milk container in just under 30 seconds.

Since you know where the fuel pump is you can see why some Stageas wont go if parked on a steeply cambered road with not much left in the tank. I will be protecting my new engine with a surge tank in the spare wheel well using my existing Walbro as a lift pump and an external Bosch to supply the engine from the surge tank.

[_Ryan_]

i do fuel filters every 20k km, read it in a service manual...

[DaveB]

Thanks guys. Yes pump & cradle is out, I will take photos if anybody's interested. I wasn't game to stick it in a bucket of petrol lol but I guess I could

Yes I have got a new Ryco filter (Z201) to replace my (near new) fuel filter, since I guess it has done nearly 45,000 K's ()

After that I might check the flow of the new one on the car. Thanks for the tip Bob. I see what you mean about the camber trouble... I don't reckon you'd need much less than a 1/4 tank and a mild left incline to lose fuel pickup!

[32TAXI]

Got power to pump + No fuel pressure before filter = Replace pump

(I had a walbro full of sand + Sock intack and not damaged = warranty)

[DaveB]

Sounds like it; had power but no pressure before the FPR on the outlet of the fuel filter in the engine bay.

I've replaced filter & blown compressed air down the lines and no sign of any blockages. If my pump is full of sand or something it could be a long process to make a warranty claim (bought off eBay about 12 months ago), so not sure if I'll get that far or not. But the only place in Adelaide that I can find who have (or will have tomorrow) a GSS-342 in stock want $250 (:S) so maybe I will have to try.

Filter didn't appear blocked either, btw - I shook it and no fuel came out, but then I just blew through it and lots poured out, so looks OK (though old - 40,000ks old). Replaced it with a nice new one.

Could I make a suggestion to those replacing their fuel filter... be prepared to change any number of the many short rubber hoses & clamps you encounter getting the bugger out, because sometimes you may need to be rather vigorous and damage can result...

[KiwiRS4T]

While you're at it Dave have you wired your pump for full battery voltage (there's a couple of how to threads in the skyline section)? Joe at the workshop says Walbros don't seem to last as long run at less than full voltage and of course they don't deliver the same flow either.

[DaveB]

Really? I thought they would last longer if they didn't work as hard... well that was my excuse for not getting around to it anyway

I have a length of 8ga cable already run to the battery; I would just need the relay and I'm all set... but the extra noise at idle... ahhhh I'll think about it.

[DaveB]

Well I got a new fuel pump today (Walbro GSS-342 - same as the old one) and mailed the 040 I bought off to its buyer.

Fitting the pump was pretty straight-forward; opted to use the old filter sock, after some cleaning and blasting with compressed air, as it looked larger and less restrictive than the new one. Getting the pipes connected up to the "lid" of the tank though, whilst getting the float and low fuel senders into the hole at the same time AND not bending them, was a *pain*.

The Walbro sure is a straightforward upgrade; it fits so well in the stock location that even the connector fits into the connector hole in the rubber grommet in the cradle.

After only the 3rd run or so, I had some trouble starting it again. I'm not sure if this is maybe related to my alarm/immobiliser now... though the pump was definitely dead before. Also my climate control unit (xanavi) has taken to switching itself off randomly all-of-a-sudden. Argh. I will pull that and investigate it and alarm at same time. Perhaps the workshop disturbed some wiring when they removed & refitted the engine.

[DaveB]

OK, fuel pump replaced, and it now starts! But, it still takes about 3 seconds or so of cranking before it fires, and then it runs pretty bad - about 500 revs - for a while until it eventually begins to run properly. It's as though it loses fuel line pressure every time I shut it off. Isn't there a one-way check valve somewhere that's meant to keep pressure in the line? Anyone know where abouts? Maybe *that*s failing...? I've replaced the pump, filter, checked all clamps, blown compressed air down the rubber & metal lines... I can't think what else could be wrong that's not fuel-rail related?

[KiwiRS4T]

OK, fuel pump replaced, and it now starts! But, it still takes about 3 seconds or so of cranking before it fires, and then it runs pretty bad - about 500 revs - for a while until it eventually begins to run properly. It's as though it loses fuel line pressure every time I shut it off. Isn't there a one-way check valve somewhere that's meant to keep pressure in the line? Anyone know where abouts? Maybe *that*s failing...? I've replaced the pump, filter, checked all clamps, blown compressed air down the rubber & metal lines... I can't think what else could be wrong that's not fuel-rail related?

When you turn the key on can you hear it priming ok? Still think its worth pulling a hose off the fuel rail and measuring the flow when you turn the key i.e time the flow and measure the resulting petrol.

[DaveB]

Yes I hear it humming a little, for about 3 seconds or so... guess I'll measure flow next.

[KiwiRS4T]

Strangely your symptoms sound like oiled up plugs but that is such a PITA to check!

[DaveB]

lol really? hmm well being a new engine maybe i should go to the trouble... in case there is a bad leak somewhere (ie. in a ring)

[Duncan]

you gotta be really careful with this sort of problem on a new motor. The first few minutes of running are really important for the rings bedding in, and if it is pumping fuel but not firing you can get "fuel-wash" which will glaze the bores and make it very hard for the rings to bed in correctly.

yes the standard setup has a non-return valve in the tank, but if you don't have it now you might just need to crank it a second or 2 longer. I've run without the valve for years.

I'm assuming from your post above that everything is OK now once it is started? get that motor run in, nice and hard, asap!

a mechanical fuel pressure guage is under $50 - grab one and put it into the pressure line - it will tell you sooo much with so little stuffing around.

[DaveB]

Good idea, thanks. Sometimes it starts first go, other times it idles bad and really low for as long as 10 seconds thereabouts (no throttle input) before returning to normal (which means revs up to 2k then back to ~1k). I've replaced the pump and the only odd thing I've noticed which is different to before, is that there's no vapour pressure when I open the cap now like there was before.