V8 Issues under load

So I'm experiencing a few issue with my Defender 3.5L V8 - Standard SU carbs.

While driving shes fine until I get to a hill, or longs straights where I'm hitting 60, so when the engine is under load - it starts to splutter and bog down, to the point I have had to pull over a couple of times going up hills, and as I pull over she dies.

Then crank her over, little gas and back working again. Pulling off in 1st then into 2nd without any problem, and if i'm still going up the hill by the time I'm in 3rd starts to splutter a little, but makes it up.

This is all on road so a far, but I would guess it gets worse off road. I've checked all the fuel, air and vacuum lines and can't see any problems so I'm a little stuck.

Anybody experienced this before, or know what it is?

Any help much appreciated!

Fuel starvation

have you got an inline filter ?

Thor1950 - My thoughts were fuel starvation, but how could I resolve it?


Dr evil - Yes, two. The one mounted below the drivers seat on the chassis, with metal lines connecting into it.
And the standard inline plastic one in the engine bay connected by rubber.

Looking at parts manual its seems they should both be there.

check to see if they're clogged only really need one of them though

you could also upgrade the pump to a facet gold flow if your standard ones on the way out

benpalmer said:

Thor1950 - My thoughts were fuel starvation, but how could I resolve it?


Dr evil - Yes, two. The one mounted below the drivers seat on the chassis, with metal lines connecting into it.
And the standard inline plastic one in the engine bay connected by rubber.

Looking at parts manual its seems they should both be there.

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First is change fuel filters, second is your fuel pump putting out enough psi and fuel flow ? For checking the carbs Gems and Wammers have good advice

Thor1950 said:

First is change fuel filters, second is your fuel pump putting out enough psi and fuel flow ? For checking the carbs Gems and Wammers have good advice

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if he gets a new pump a facet is self regulating on pressure, should be running 5-8psi ish I think but either way the gold flow pumps will work to the required pressure

Dr_evil said:

if he gets a new pump a facet is self regulating on pressure, should be running 5-8psi ish I think but either way the gold flow pumps will work to the required pressure

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You think the jets/carb could be dirty? just need a good cleaning. lord knows how old they are, and if it has stood for a long time and is just gummed/varnished on the inside. Could try a good dose of carb cleaner at 1/2 throttle and spray it heavily until it just about stalls out

Thanks Guys,

I have just replaced both fuel filters and the fuel pump (with standard LR one)! I will try run it with only one filter to see if it helps.

Thor1950 said:

You think the jets/carb could be dirty? just need a good cleaning. lord knows how old they are, and if it has stood for a long time and is just gummed/varnished on the inside. Could try a good dose of carb cleaner at 1/2 throttle and spray it heavily until it just about stalls out

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Hmm, yes it has stood for a while, nearly two years! I will give the carb cleaning a go also.

Thanks

benpalmer said:

Hmm, yes it has stood for a while, nearly two years! I will give the carb cleaning a go also.

Thanks

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That is the probable cause. Drain the gas tank and fill with fresh petrol, Could have a bunch of water in fuel tank from condisation.

Thor1950 said:

That is the probable cause. Drain the gas tank and fill with fresh petrol, Could have a bunch of water in fuel tank from condisation.

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I have just filled the tank up today, but I'll drain half out that should get rid of any water, but I have just done a 2hr journey.

benpalmer said:

I have just filled the tank up today, but I'll drain half out that should get rid of any water, but I have just done a 2hr journey.

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Then go to plan B put in a heavy dose of dry gas. We use that in our boats when we store them. Just had my boat out last week, and had be stored for a year, put in dry gas product and it fired up ran nice.

Could well be blocked jets, not to bad to service carbs, just remember how many turns the adjustable bits had

Thor1950 said:

Then go to plan B put in a heavy dose of dry gas. We use that in our boats when we store them. Just had my boat out last week, and had be stored for a year, put in dry gas product and it fired up ran nice.

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Dry gas, not heard of that I will check it out. Just flushed some of the tank no water came through with it. But I will do the dry gas just to be sure, as it has sat a while.

Discomark10 - thanks, I will have a look for a "how to service SU's" guide now then!

benpalmer said:

Dry gas, not heard of that I will check it out. Just flushed some of the tank no water came through with it. But I will do the dry gas just to be sure, as it has sat a while.

Discomark10 - thanks, I will have a look for a "how to service SU's" guide now then!

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this type of stuff

Halfords

is your ignition advancing

Check compression early v8 tipped heads and rover eventually removed row of bolts

Not a bad idea to check the timing at a few different rev ranges if you have a gun, check when its advancing, should be fully advanced at 3500 if I remember correctly. Is it a certain rev range it does it at?

Thanks for all the responses so far; so to cover what I did to fix the problem over the weekend, I started out trying some of the stuff brought up here already:

Took the 2nd inline fuel filter off - no affect
checked fuel filters - all OK
Drained fuel out of the tank to check for water - none found
Changed a vacum hose as it looked ropey - no affect
Clean up all the coil connections - no affect
Took off and cleaned the carbs - Which a made it worse, it now struggles to run on ideal and eventually cuts out, even with the choke on.

I have a fuel pressure gauge coming tomorrow to make sure that is 100%.

Ianski / Discomark10 - I can get hold of an timing gun, I will check this out also. It does do it at mid to top RPM in most gears but 1st and 2nd are normally fine, but it also does it at lower RPM if i'm going up a hill. It revs up fine out of gear and will happily rev up and down like normal out of gear.

fanatic - OK good shout I will check out the compression. What do you mean by tipped heads? And which bolts?

Thanks for the help so far!