My V8 has no power and runs as rough as a dog!

[nzlromacka]

Gidday lads.....

I posted this same message on the NZLROC Forum a few days back, and the lads there reckon I should replace the fuel filter, which I will do tomorrow...however, having found a forum dedicated to the S1, I thought I'd also ask your advice and see what you guys think?

As an aside...I don't have a parts Manual for the V8...what type of fuel filter is used?


I let the V8 warm up to normal operating temperature before setting
out, all seemed well and I pulled out into traffic, 1st gear good,
second gear ok.... 3rd gear...the engine spluttered and lost power. I
pulled over assuming the engine was still cold, but it continued to do
this for about 5k's until I gave up and limped back to the workshop.
Its a strange fault. The V8 idles well, and pulls away in 1st /2nd
OK...but as soon as it gets up to around 50-60km per hr, it loses all
power, and with my foot to the floor, there is no increase in engine
revs. The truck refuses to go faster than 60km/h...I know they have
restrictors fitted, but this seems extreme!!

Anyway, I was after your thoughts as to why my V8 is behaving like
this, why can't it go past 60 km/h and why does it have no power in
3/4th gears?

All help appreciated lads!!

[Larry]

Can't help with the problem you've got (although when mine did that it was a loss of compression due to knackered piston rings!I'll keep my fingers crossed that someone comes up with easier option for you to fix)

You can get the manuals, including the SIII parts manual here:

Manuals download

[primsil]

The fuel filter or the fuel pump, my 75 Rr was having similar symptoms when the fuel pump packed in, finally gave up completely just after. They have the same pump.

[stirlsilver]

In first and second gear does it splutter when you put your foot to the floor and get to high revs?
Stirling

[flyingkipper]

Hope you don't mind if I stick my oar in here, because mine is the same - starts easily from cold, idles smoothly, and if you drive around with a light right foot and don't go over about 40mph, you wouldn't think there was anything wrong. If you want to get some speed up though, it just splutters when you put your foot down.

I have changed the plugs all the ignition stuff (coil, plugs leads, condenser, etc..) and it is now a bit better, but still misfires when you open up the throttle at speed.

I reckoned it must be carb/fuel related, so I checked the piston action and diaphragm in the strombergs. All ok with no splits.
Then I had a feel of the vacuum in each carb at idle by holding hands over each intake with the air intake piping off. Really obvious difference, so carbs obviously not balanced properly. Then I blocked off each carb in turn whilst it was idling. When running on one of the carbs, it would idle ok, but then if you switched over and blocked off the other instead, it died straight away.

So, is one of my carbs starved of fuel? Is that why it doesn't run properly at bigger throttle openings at speed? Because its getting loads of air and not enough fuel?

Any ideas appreciated before I start messing with the carbs!

Cheers,
Noel.

[Larosto]

Hi,

I think you should look at your carbs. Are the diaphragmas ok, and are the carb-pistond moving easy?
If you can`t find a mistake there, you should look at your ignition, especialy at the distributor. Maybe the contacts are worn, or the spark goes the wrong way, that means perhaps a bad cable or so.

good luck

Horst

[nzlromacka]

Hi guys,

Well, this is my progress to date....

I have put 10L of fresh new fuel into the side tank for the purpose of
this test. The truck was running on the rear tank when this fault
occured. The side tankw as almost empty and the truck has used this
tank predominantly when running.

I have removed the fuel filter housing and replaced the existing
filter element with a RYCO R2045P which is almost a replica of the
badly corroded filter that remained in the filter housing.

Once this was back in the truck, I disconnected the fuel line from the
inlet to the AC type filter housing to make sure I had fuel flowing
from both the side and the rear fuel pumps. Fuel flowed with the
selector switch on either pump setting. So I have assumed the pump
and the fuel lines to the filter is OK.

I then reconnected the fuel line to the filter housing and then
disconnected the fuel line as it enters the right hand side Solex carb
(as you look at the engine from the front of the truck), again, fuel
flowed well to this point from both pumps and looked to be nice and clean.

So, so far so good... I reconnected the fuel line. And tried to start
the truck. After a bit of cranking (starting with full choke as the
engine was cold) to no choke at all. The truck would'nt even fire! I
have now drained both 12V starting batteries, so have them on the
charger and will try again tommorow...

I can only assume that it is now a blockage in the carbs or another
fault causing the fault.... any other suggestions guys? I note two
black screw caps on the top of the carbs, what are these for?

All help much appreciated at this point!

Cheers

[primsil]

Hi Andrew. I would check the fuel at the return line, where it connects at the drivers side carb. Then you can be sure of no blockages to there, if its fuel then it must be in the carbs if that is okay.
The black caps are the dampers on the pistons. The pistons should move freely and should have oil in them. You can remove the cover screws (4) and check the diaphrams are not split.

Did you check for spark. What dissy are you running, has it the shielded one or the mallory replacement. Is it still 24v or now 12. Might pay to put a timing light on it and check the timing while you are there.

[nzlromacka]

Gidday primsil, good to see another Kiwi on here!

To anwser your questions.....

Yes, it is still running the military 100A alternator and the vehicle has not been converted to civilian 12V.

I only have experience with the Zenith 2.25 ltr carb, so I appreciate your advice on the twin solex setup on the 3.5 V8...

I have removed the black plastic screws and they both have oil on the ends of the dampers.... is this OK or should there be more/less oil? I can't tell what type of distributor I have, only that it has NZ Army stamped on a tag located on it. The HT lead from the centre of the dissy cap leads to a large wire mesh enclosure located below the radiator fill/overflow bottle...I assume this is a mil spec 24V coil?

Will check for spark and check the fuel at the return line on the drivers side carb and let you know how I get on....

Please let me know what you think on the above!

[nzlromacka]

Another update... I have good clean fuel flow at both carburettors and also a good blue spark on the plug I tested (#6 cylinder)...

Looks like it has to be a carb blockage issue from here?

[primsil]

If the dampers have oil on them that should be okay, the book says 6mm from the top but it is a pain to try to check that in the vehicle.
Does sound like carb(s) then. Did you say you had recently swapped over tanks, could have been some dirt got through if one had been unused for a while.

[stirlsilver]

Thing is with these carburettors is that you really need both to be blocked up to stop the engine... If one was working you would hear it try to start and possibly even run.

One way to see if it is insufficient fuel is by taking off the large aluminium elbows that lead into the carburettors and while you are cranking momentarily block the carburettor inlets with your hands so fuel is sucked up. Then release to see if it fires.

You obviously don't want to do this if the problem is that it is flooding because it definitely won't help. Does it smell of fuel when you crank?
Stirling

[Larry]

After mine was stood for a while it wouldn't run well. When I finally got round to stripping the carbs I found that the fuel had dried up in the float chambers and partially blocked the filter and float inlet valve with white crud. Cleaned it up and replaced one of the inlet valves (and the needles after I dropped one and it broke! Doh!). It ran perfectly after that.

It may be that these valve/filters are partially blocked and allowing enough fuel in to run on low revs, but when you want more revs and therefore more fuel, it's causing fuel starvation.

The restrictors by the way don't make that much effect on normal performance, and it should still be pretty respectable with them fitted (you'll notice if they're removed though! ).

[Andy Dawe]

Mine would misfire when revved or under load but drive, start and run fine. After weeks of playing with carbs, plugs and timing I discovered that the coil and ballast resistor wiring although looking fine was at fault. I chopped all the spade connectors off and soldered on new ones. It runs like a dream.

[nzlromacka]

Gidday guys,

Firstly, thanks to you all for all the advice, its really appreciated!

Freeshly charged batteries today and unfortunately the truck will not start at all now...

So, I find myself looking at the twin carb setup on top of the engine.... I have been advised that the first thing to do is "clean the bowls"...now on the 2.25 ltr Zenith carb that I have worked on, this is easy...but on the twin Solex units, I am not so sure...

What should I be looking for here? What can I clean without pulling the entire carb apart which i feel is possibly beyond me as I have no experience with the type on the vehicle.... how do I remove the bowls? I assume they are at the bottom of the carb, and are held in place with 4 screws? The top cover has an another 4 screws which can also be removed? Where would crud from a dirty fuel line most likely end up?

Sorry for all the questions...

Cheers lads!