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3.5 v8 engine dies under load
richardh - 24/11/12 at 03:40 PM

Mine idles fine but then after about 30 miles or so, it really starts kangarooing and dies.
I changed the coil and plugs.
Distributor cap is new too

Leads look fine and spark is good.

Anyone got any ideas please?

Cheers

Richard


SCAR - 24/11/12 at 04:20 PM

If the sparks ok most likely fuel
Could be fuel starvation if your tank is not ventilating effectively (causing an in tank vacuum), when it happens try removing the fuel cap to see if it resolves or could be heat transfer to the carbs causing fuel evaporation, is the engine (carbs) getting overly hot?


Chippy - 24/11/12 at 04:23 PM

Had one years ago that had smilar problems, mainly just wouldn't rev, turned out to be the fuel filter causing the problem. May be worth checking. HTH Ray


blakep82 - 24/11/12 at 04:28 PM

condenser and points?


marcyboy - 24/11/12 at 04:52 PM

quote:
Originally posted by richardh
Mine idles fine but then after about 30 miles or so, it really starts kangarooing and dies.
I changed the coil and plugs.
Distributor cap is new too

Leads look fine and spark is good.

Anyone got any ideas please?

Cheers

Richard


As stated by someone else...possible fuel starvation...worth a look.

My old 3.5 rover had the same issue...breather pipe on top off the tank was getting pinched between the tank and the bodywork...she ran for 20 mins or so then died, if i waited about 10 mins she'd start...for at least 20 mins or so... the giveaway should been the crushed fuel cell...


deezee - 24/11/12 at 05:00 PM

Is it a recent problem, have you recently changed anything? Whats your fuel setup? What carbs? When you say it dies after 30 miles, is that an hour of driving or what? After it dies will it restart after 5 mins? It sounds like fuel starvation. But need more info to narrow it down, or you'll end up with 10 guesses of parts to change!


britishtrident - 24/11/12 at 05:38 PM

Most likely cause is lack of fuel flow --- first priority is check the tank breather if not that check for debris floating in the tank and check the filters, also disconnect both inlet and outlet to pump and blow back the fuel lines in reverse direction to normal flow.

If it not fuel related then if your V8 has the early SD1 type dizzie with a ribbon cable inside the distributor these can give trouble..

[Edited on 24/11/12 by britishtrident]


wilkingj - 24/11/12 at 05:51 PM

Is the coil getting hot?

As what the rest said. Deffo check fuel filter, and might be worth checking fuel flow / pressure, but be careful with a hot engine, and have a fire extinguisher ready.
Could be the fuel pump playing up when it gets hot. ie reducing the flow, so fuel starvation.
What sort of fuel pipe have you got? ie is it old and maybe collapsing?
What sort of carb?
If its a 4 barrel job, you can get a Phenolic spacer (Heat insulator).
I put one on mine, but it didnt really need it.
Usually they are only needed in hotter climates. They stop evaporation in the carb / float chamber.

Whats the Water temp doing?
Is the Thermostat opening?



Once it starts playing up, does it clear if you stop wait 5 mins and start again?
or is it only after 30 miles when its got hot and then doesnt go until its got cold?

Next time it does it. Stop engine. The jump out and open the fuel cap and listen (ear close to the cap) and see if there is an air rush, ie a vacuum in the tank. Its a good pointer. Could be as simple as a blocked vent in the cap or however you vent your tank.

Cant think of much more.




[Edited on 24/11/2012 by wilkingj]


mark chandler - 24/11/12 at 07:00 PM

I have. Had a couple that when hot have died completely, rotor arm for me.


richardh - 24/11/12 at 07:58 PM

Cheers folks


Tank is new, fresh fuel
Line and filter are new
It's on a regulator at 2psi with a 2-3psi facet electric pump which is beneath th rear chassis. Ticks fine and pumps through to end of pipe at carb ok.

If there was rubbish in it then it would surely stall well before 30 plus miles

Wondered if it is electrical, something breaking down at higher revs or when warm

Engine temp says normal
Fan is not viscous but electric on a separate switch
Thought the coil was warm ish so I had a spare an swapped it with no joy

I drove to mot place about 20 miles away, they had it idling etc
Turned off for about 20mins to do paperwork
Got 16 miles home and she's stalling.

Did the same on the same journey but not as bad.
Carb is a 38dgas that came off a running car

Can't tell if thermostat is opening

Tank has a breather hose looped up and over an back below tank level and its clear of obstruction.

It's an sd1 dizzy with a recently new cap on it. It looks fine.

Leave it to go fully cold at seems to be fine.


mark chandler - 24/11/12 at 09:08 PM

Hummm could just be carb freezing up, it you leave for a few minutes is it then fine?

38dgas is not a big device, ford had the snorkel pulling from the exhaust manifold on light loads with flappy trickery from what I remember on capri's and granada's.


richardh - 24/11/12 at 09:23 PM

If I leave for a few mins it starts, runs for about 100 yards then starts doing it all over again.
If left o cool overnight fo example it seems to be ok


scudderfish - 25/11/12 at 09:55 AM

38DGAS? I used to have one of those on my car.... Oh wait....

I had a similar problem that was electrical. It eventually turned out that the regulator on the alternator was goosed and the amp was putting out too many volts. This caused a slow failure of the amplifier between the dizzy and the coil by cooking it. It would drive for a while and then die. Leave it a while and it would run again. However the amp finally packed up and then it wouldn't run at all.

Regards,
Dave


Andy S - 25/11/12 at 10:10 AM

Its most likely to be the ignition module - what you got 35DE8 35DM8 or 35DLM8? - I would think that all 35DE8 OPUS systems would be pretty well dead by now the DM is separate from the dizzy in a alloy can and they are well past there best especially when peeps miss out the ballast and fry them - The 35DLM8 is the least you should have fitted with the module on the side of the dizzy but these have a pretty limited life span and if original would be well overdue for a replacement.

Andrew

ETA

Also worth disconnecting any tacho associated with the circuit to remove any chance of that breaking down internally.

[Edited on 25/11/12 by Andy S]


richardh - 26/11/12 at 08:29 AM

hi, how can i tell which one i have? not sure where to check numbers etc.

so it could be regulator, dizzy, amplifier, condensor, points.

doubt its fuel related from the checks i've done

cheers


richardh - 26/11/12 at 08:46 AM

ok, i've got the dlm8 version.


scudderfish - 26/11/12 at 09:14 AM

There is a comprehensive PDFs of tests linked to here http://www.vintagemodelairplane.com/pages/Downloads/Rover_Tasters/Ignition02.html. Don't let the domain name fool you, that website is chock full of V8 Rover SD1 stuff.

It may also be worthwhile signing up for http://www.v8forum.co.uk. What they don't know about the RV8 can be written on a Higgs boson.

Regards,
Dave


richardh - 26/11/12 at 09:15 AM

Cheers Dave