V8S Overfueling
Discussion
Hi there I'm an interloper from the TVR-S forum looking for some help and advice on the 4.0 V8 pre cat engine 1992. Hoping that you'll help out a fellow TIV'er.
I was out for a run yesterday with some fellow TIV'ers (and a Porsche and a Ferrari) and she was running really well. Any way after a brief stop she was reluctant to start and ran like a bag of nails. Wouldn't rev above 3,500 rpm and pulled like a 2.0 4 cyl.
Hoped that a good thrash would clean it out (ever an optimist) but it got worse and after a mile pulled into a layby to have a look under the bonnet. My mates had seen huge white clouds coming out the back of the car.
One of my mates pointed out a wet patch on the exhaust manifold. Touch and smell said that it was neat petrol. It was weeping out from the manifold gasket on the number 2 cylinder. The smell from the back of the car was fuel vapour coming out of the exhaust even with the engine off.
I tried disconnecting the AFM on the advice of a friend and this made no difference to the rough running.
My strong suspicion is that the injector in number 2 cylinder has jammed wide open squirting loads of neat fuel into, and back out of, the cylinder and down the exhaust. If so then hoping that an injector recon will fix it?
So the question is does this sound feasible and what else could/should I check before I have to give up and get it dragged into a workshop?
Bob
I was out for a run yesterday with some fellow TIV'ers (and a Porsche and a Ferrari) and she was running really well. Any way after a brief stop she was reluctant to start and ran like a bag of nails. Wouldn't rev above 3,500 rpm and pulled like a 2.0 4 cyl.
Hoped that a good thrash would clean it out (ever an optimist) but it got worse and after a mile pulled into a layby to have a look under the bonnet. My mates had seen huge white clouds coming out the back of the car.
One of my mates pointed out a wet patch on the exhaust manifold. Touch and smell said that it was neat petrol. It was weeping out from the manifold gasket on the number 2 cylinder. The smell from the back of the car was fuel vapour coming out of the exhaust even with the engine off.
I tried disconnecting the AFM on the advice of a friend and this made no difference to the rough running.
My strong suspicion is that the injector in number 2 cylinder has jammed wide open squirting loads of neat fuel into, and back out of, the cylinder and down the exhaust. If so then hoping that an injector recon will fix it?
So the question is does this sound feasible and what else could/should I check before I have to give up and get it dragged into a workshop?
Bob
SILICONEKID340HP said:
Your car might be better off on the road .... Does it ever leave the garage ? you don`t want to spoil the chassis
Hmmm, on the road again is exactly where I am looking to get it and I presume that my chassis is as prone to rust as yours? The car certainly gets used in all weathers, when it's running, after all it is a TVR...Bob
Bobhon said:
SILICONEKID340HP said:
Your car might be better off on the road .... Does it ever leave the garage ? you don`t want to spoil the chassis
Hmmm, on the road again is exactly where I am looking to get it and I presume that my chassis is as prone to rust as yours? The car certainly gets used in all weathers, when it's running, after all it is a TVR...Bob
Chilliman said:
Bob, the only suggestion I have is if you're getting petrol sprayed/dropping onto the exhaust manifold(s) then for Gods sake don't try starting it again without a fire extinguisher (or two) to hand......
Thanks for the advice. I got myself recovered home rather than try to drive her when I saw the raw fuel on the exhaust manifold.The fuel is leaking out of the exhaust manifold through the blow in the manifold gasket (the usual exhaust blow point). Which means that there's loads of unburnt fuel going down the exhaust pipe.
It used about 1/8th of a tank of fuel in a couple of miles, serious overfuelling huh...
Bob
My strong suspicion is that the injector in number 2 cylinder has jammed wide open squirting loads of neat fuel into, and back out of, the cylinder and down the exhaust. If so then hoping that an injector recon will fix it? This is your quote Bob.
If number 2 injector is the problem check for wet number 2 plug. Check all plugs on that manifold side for wet or dry. Good luck Eddie (My PC Vista is misbehaving for quote reply!)
If number 2 injector is the problem check for wet number 2 plug. Check all plugs on that manifold side for wet or dry. Good luck Eddie (My PC Vista is misbehaving for quote reply!)
Edited by EGB on Monday 9th January 22:32
It does sound a bit funny - if you have neat fuel being squirted down a hot exhaust (when the car was running) that would surely be burnt - would that cause the smoke mentioned or could that be steam and the fuel something else? Probably not too helpful but I'd be interested to know the outcome so let us know. In the meantime the plugs out and look at them is a good starting point.
Jim
Jim
Thanks for all the replies so far. I will try to get under the bonnet this weekend and try out some diagnostics.
How would I be able to test if the Fuel Pressure Regulator is gone?
I'll look on eBay tonight to see how much a Regulator goes for.
I have been advised to pull out the fuel rail, with the injectors still attached, and to turn on the ignition to get the fuel pump running, but not to turn the engine over. This, I am advised, will pressurise the fuel rail and no fuel should leak out as all of the injectors should be closed. So if any injector is squirting out fuel then it's stuck open.
Obviously needs a bucket to catch any fuel that does come out.
I've had a firm recommended by a fellow PH'er that cleans out injectors at a reasonable price, so it may be worthwhile getting them done anyway.
How would I be able to test if the Fuel Pressure Regulator is gone?
I'll look on eBay tonight to see how much a Regulator goes for.
I have been advised to pull out the fuel rail, with the injectors still attached, and to turn on the ignition to get the fuel pump running, but not to turn the engine over. This, I am advised, will pressurise the fuel rail and no fuel should leak out as all of the injectors should be closed. So if any injector is squirting out fuel then it's stuck open.
Obviously needs a bucket to catch any fuel that does come out.
I've had a firm recommended by a fellow PH'er that cleans out injectors at a reasonable price, so it may be worthwhile getting them done anyway.
If its the 3.9 pre serp 14cux system, theres not an easy way to test the actual fuel pressure, as you need to put a T piece in the fuel line feed to the fuel rail to attach a pressure meter to. The latter serp engine has a take off on the fuel rail. I suppose you could put a fuel line on the output side of the regulator, and feed it into a glass jar, and cycle the ignition on. The regulator should open and squirt fuel into the jar when the pump runs. Before you mess around with pulling all the injectors out,( I would not advise this test method!!) why not drop out all the plugs and look at the colour? If the fuel pressure is high,or the AFM has failed all the plugs will be black, if its an injector that has failed only that cylinder will be affected. As for the AFM, if its voltage goes high it will over fuel the engine badly, but I've never come across neat fuel or white exhaust! I have also come across random injector firing with a failed chip in the ECU that floods the engine, but thats combined with the fuel pump running all the time, where it should only pulse on for a second or two when the ignition is first turned on.
blitzracing said:
If its the 3.9 pre serp 14cux system, theres not an easy way to test the actual fuel pressure, as you need to put a T piece in the fuel line feed to the fuel rail to attach a pressure meter to.
I don't think there is much doubt that there is fuel pressure! 
In any event, if you want to check it on a Hotwire, why not save time by removing the fuel temperature sender (which plugs directly into the fuel rail) and replace it, for the test, with your fuel pressure gauge. You will have also have to power the fuel pump directly or otherwise the MAS will turn it off after a sec. What can cause this problem with one injector? In order of likelihood;
1. it will occur if that injector wiring is earthed. The injector will keep spraying continuously while the piston is moving at force, up and down. It will also fill the sump and eventually hydrolock the entire engine
2. the injector has failed open. Which is a bit less likely but will produce the same events as #1
3. it is possible but much less unlikely that the 'puter has a problem. ECU problems involving injectors normally express themselves on the whole bank of injectors, the 4 right or the 4 left.
+8
plushuit said:
In any event, if you want to check it on a Hotwire, why not save time by removing the fuel temperature sender (which plugs directly into the fuel rail) and replace it, for the test, with your fuel pressure gauge.
+8
Doh... why did I never think of this... I can make an adapter with an electrical fuel pressure sensor, and gauge you can read in the cabin, powered of the cigarette lighter so its portable. Its always been difficult to do pressure tests under full load with a gauge directly on the fuel rail.+8
So with some telephone help from Craig at Dyno Torque the fault was diagnosed last weekend as a sticking open injector on number 4 cylinder. Craig seems to have a lot of knowledge on Rover V8's and he says that he's seen this fault before, usually the over fueling causes a hydraulic lock in the engine, bending a con rod and generally toasting the engine. 
But mine didn't actually stop so it looks as if I've gotten away with it.
So I dropped the car off with him today (surprising how well it runs on only 7 cylinders with the No4 injector disconnected). It's having a recon injector fitted, an oil leak cured and the oil and filter changed (petrol in the sump).
Speaking with Craig he seems to specialise in LS conversions to the car of your choice. He's showing a couple of LS Cerbies and an LS Saggy on his website.
Looking to get the car back this time next week and I'll let you know how it goes.
Bob
But mine didn't actually stop so it looks as if I've gotten away with it.
So I dropped the car off with him today (surprising how well it runs on only 7 cylinders with the No4 injector disconnected). It's having a recon injector fitted, an oil leak cured and the oil and filter changed (petrol in the sump).
Speaking with Craig he seems to specialise in LS conversions to the car of your choice. He's showing a couple of LS Cerbies and an LS Saggy on his website.
Looking to get the car back this time next week and I'll let you know how it goes.
Bob
Gassing Station | Griffith | Top of Page | What's New | My Stuff