Vauxhall 16v Fuel Problem
Strax
Nova fitted with Calibra 16v 2.0XE engine.
Bosch Motronic 2.5
FSE Adjustable pressure regulator
The problem:-
Car went through a rebuild which included the removal and refitting of
the engine and gearbox. When I got the car back the fuel pump whined
a bit more than usual. . Ran the car for another 1000 miles then the
car started to splutter and overfuel. When checked the fuel pressure
was pulsing between 3-6 bar (this was sitting at idle). This would
last a few seconds before the car got choked with fuel and cut out.
What we have tried so far:-
Replaced FSE regulator with standard regulator. No change
Replaced Fuel pump (old one was noisy and on it's last legs)
Replaced Fuel flow damper
Replaced Fuel Filter
Checked out the engine on a scope. All looked OK, pulses were correct
(according to my mechanic friend)
Plugged engine into scanner. Seemed OK, Showed Lambda fault (probably
the overfuelling)
Checked the Vacuum to the regulator. OK
Phoned up the Bosch Technical helpline (at £1 a min!) they suggested
everything we had already tried. Left them scratching their heads!
Next week we will be replacing the fuel tank and the fuel lines.
(Would have been this weekend apart from being sent the wrong fuel
tank!)
The question is....is there anything else that we have not thought of?
My mechanic has so far spent 3 days on this problem with no joy...
So any suggestions...
Strax
PNG Scotland
'If it ain't broke, it ain't mine.
Graham
(Strax) wrote:
>The car :-
>
>Nova fitted with Calibra 16v 2.0XE engine.
>Bosch Motronic 2.5
>FSE Adjustable pressure regulator
>
>The problem:-
>
>Car went through a rebuild which included the removal and refitting of
>the engine and gearbox. When I got the car back the fuel pump whined
>a bit more than usual. . Ran the car for another 1000 miles then the
>car started to splutter and overfuel. When checked the fuel pressure
>was pulsing between 3-6 bar (this was sitting at idle). This would
>last a few seconds before the car got choked with fuel and cut out
>What we have tried so far:-
>
>Replaced FSE regulator with standard regulator. No change
Is the pressure still the same with the std reg? Is it still
fluctuating? Personally I do not like the FSE regs, pressure
differences and pulsing are not unusual in my experience. If it is the
same (high), then connect a temp pipe to the rail return and feed into
a large container, this will bypass the return lines to the tank,
crushed or collapsed pipes could give high pressures. fit your
pressure gauge in and see what you get now. Take care with the petrol
- no fires please !!!! (I assume you have an accurate gauge)
>Replaced Fuel pump (old one was noisy and on it's last legs)
If its been working at 6 bar, that prob finished it off.
>Replaced Fuel flow damper
>Replaced Fuel Filter
>Checked out the engine on a scope. All looked OK, pulses were correct
>(according to my mechanic friend)
>Plugged engine into scanner. Seemed OK, Showed Lambda fault (probably
>the overfuelling)
>Checked the Vacuum to the regulator. OK
Have you checked, and double checked the cam timing. Very easy to get
wrong on this engine and when out can give a good running engine but
not spot on.
>Next week we will be replacing the fuel tank and the fuel lines.
>(Would have been this weekend apart from being sent the wrong fuel
>tank!)
Try the temp return first, If the pressures are ok then, the prob is
between the rail and the tank, work your way back to find the
blockage. While you have the temp return feed check fuel delivery and
make sure its not pulling a lot of air that could be causing the
pulsation.
Graham
PumaRacing
>From: png.Scotland@bigfoot*nospam*.com (Strax)
>Date: 28/10/98 17:53 BST
>Message-id: <3637483...@news.clara.net>
>
>The car :-
>
>Nova fitted with Calibra 16v 2.0XE engine.
>Bosch Motronic 2.5
>FSE Adjustable pressure regulator
>
>
>The problem:-
>
>Car went through a rebuild which included the removal and refitting of
>the engine and gearbox. When I got the car back the fuel pump whined
>a bit more than usual. . Ran the car for another 1000 miles then the
>car started to splutter and overfuel. When checked the fuel pressure
>was pulsing between 3-6 bar (this was sitting at idle). This would
>
>What we have tried so far:-
>
>Replaced FSE regulator with standard regulator. No change
>Replaced Fuel Filter
>Checked out the engine on a scope. All looked OK, pulses were correct
>(according to my mechanic friend)
>Plugged engine into scanner. Seemed OK, Showed Lambda fault (probably
>the overfuelling)
>Checked the Vacuum to the regulator. OK
>everything we had already tried. Left them scratching their heads!
>
>(Would have been this weekend apart from being sent the wrong fuel
>tank!)
>
>
>My mechanic has so far spent 3 days on this problem with no joy...
>
>
>So any suggestions...
>
>
Change your mechanic! This is fairly straightforward. The fuel pressure can
only be determined by the pressure regulator or any other restriction in the
system. A common tweak on fuel injected race cars where the rules only allow
bog stock engines is to "massage" the fuel return lines with a rock and claim
an excursion onto the grass if the scrutineer calls you. By the sound of things
(reading between the lines) your recent "engine and box out rebuild" has been
an excursion onto the grass type experience. Anyway, whatever - either you have
a crushed fuel return line or you have still not substituted a good pressure
regulator during your tests. Why on earth are you replacing the fuel tank -
that can have no effect on the system pressure? (unless it's empty of course -
lol)
Dave Baker at Puma Race Engines (London - England) - specialist flow
development and engine work.
Chris Wilson
png.Scotland@bigfoot*nospam*.com says...
> The car :-
>
> Nova fitted with Calibra 16v 2.0XE engine.
> Bosch Motronic 2.5
> FSE Adjustable pressure regulator
>
>
> The problem:-
>
> Car went through a rebuild which included the removal and refitting of
> the engine and gearbox. When I got the car back the fuel pump whined
> a bit more than usual. . Ran the car for another 1000 miles then the
> car started to splutter and overfuel. When checked the fuel pressure
> was pulsing between 3-6 bar (this was sitting at idle). This would
> last a few seconds before the car got choked with fuel and cut out.
<snip>
> So any suggestions...
Check the return line from the regulator/fuel rail is totally
unobstructed,uncrimped,etcetera.Remove the engine end,and blow down
it.You should be able to move the fuel back to the tank easily,with your
lung pressure.Or try a pressure gauge in the return line.Sounds like it
could be partially blocked,possibly intermittently.
--
Best Regards,
Chris Wilson
http://www.f3.u-net.com
Strax
on. We had suspected the fuel return lines, and that is why we were
going to replace the fuel lines. The main feed from the pump to the
engine had been joined in a couple of places through the years, so we
were going to replace that to eliminate any chance of air being drawn
into the lines
The reason we were going to change the fuel tank was we suspected that
we were getting contamination (rust) going through the lines. The
fuel filter that we took off originally did seem to have dirty petrol
in it. Another reason was that the original tank was for a carb fed
engine. I wanted to change to a GTE tank which has a swirl pot inside
and also a larger pick up pipe.
regards
Strax
PNG Scotland
Graham
wrote:
>Thanks for all the replies. This will give us something else to go
>on. We had suspected the fuel return lines, and that is why we were
>going to replace the fuel lines. The main feed from the pump to the
>engine had been joined in a couple of places through the years, so we
>were going to replace that to eliminate any chance of air being drawn
>into the lines
Air will not enter via the feed pipes all you could get would be a
leak :-( BUT its best to have as few joins as possible. Remember
to use good quality fuel injection hose, not carb rubbish. BTW some
injection hose on the market is NOT suitable for unleaded petrol, over
a period of time it may deteriorate. Check to see it has "unleaded
spec" or similar wording printed on the hose exterior.
>The reason we were going to change the fuel tank was we suspected that
>we were getting contamination (rust) going through the lines. The
>fuel filter that we took off originally did seem to have dirty petrol
>in it. Another reason was that the original tank was for a carb fed
>engine. I wanted to change to a GTE tank which has a swirl pot inside
>and also a larger pick up pipe.
>regards
>
>Strax
That's why I suggested checking the delivery (after the pressure reg)
for air, just had a feeling that this was a none standard setup that
had the wrong tank for fuel injection............. ;-)
Graham