SLROC Forum
General Category => TECHNICAL CHAT => Topic started by: bertracoon1616 on October 17, 2010, 01:34:44 PM
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Hey guys.
Im in dire need of someone who knows their carburettors!
Ive got an 89 V8 discovery with SU carbs but it just will not draw fuel through them. They were bought new just over a year ago and were working fine to begin with but it stalled one day and has never been right since.
Ive tried everything i can think of to get them running, had them to bits and cleaned all the fuel pipes and needles ect.
Im genuinely at a loss.
Can anyone help me or give me the number of someone in the Angus, Forfar area who could give me a hand or some tips.
Cheers
Alasdair Tannock.
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Fuel pump getting up to pressure? Cleaned ALL fuel filters (is there one inside tank on pick-up pipe?) Blown through feed and return fuel lines? Will it fire if you squirt in some "Easi-Start" or similar volatile fuel?
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The fuel pump was also replaced when the carbs were and there is plenty of fuel coming out the pipe when i take it off the inlet for the carb.
I havent cleaned all the filters but im not entirely sure where they all are. The pump in the fueltank has been replaced by a "Facet" one under the bonnet (ive been told they were notorious for breaking down and this is the most common solution)
The car has been messed with quite a bit and looks as if a fair bit of it has been botched so im not entirely sure what all the bits of hose are doing!!
As for the Easi-start method, if i pour fuel straight into the block through the air intakes it does fire so im assuming its not the sparks but it does need a tune.....BIG TIME!
Also i just took it for a tow and put it in gear and it sounded like it was trying to fire ("pop splutter splutter bang") and i think it may have run for about 5 seconds but it still wont start.
If i put up a photo of under the bonnet would that help?
Thank for the fast reply.
Ally Tannock
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Are you sure your timing is set correctly? Definately not got the firing order mixed up or set the timing to wrong top dead center. Even badly tuned SU carbs should get you running aslong as there is fuel getting to them you will run poorly but it should start for a while atleast. Are you getting any blow back through the carbs when it does fire?
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Are the needles rising properly? I'm not 100% up on SU'd becuase I have strombergs, but if you wanted me to take a look then maybe we could arrange something? I am at Kinross so not a million miles away.
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Hey
Im certain that the timing is set up properly ive checked it several times, there is just no fuel coming through the carbs, the needles only flutter up and down when its turning over and even if i lift them manually there is still no fuel coming thro
"rangerovering", i may take you up on your offer, are you ever up this way, (forfar)?
Cheers again guys, im also now looking at converting it to diesel!
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Nooooo don't do a diesel! The fuel of satin >:(
Will PM you and see if we can arrange something?
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Nooooo don't do a diesel! The fuel of satin >:(
Satin - Should run pretty smooth then !! ;D
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d'oh meant to say Satan! Thought it looked a bit funny with an "i" righ enough :D
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Hi
Had a read of all this and:
You say there is fuel at the carb inlet pipe so (I assume the pump is ticking and picking up fuel) try and start it then remove a spark plug. It should smell of petrol. SU's don't really flood so often don't smell at all esp if choke faulty, see below.
If so is there a spark? Take care and an assistant will help!
You say the timing is correct .......... so hasn't been altered since it was running ok? If it has it could easily be 180 deg out.(which causes popping banging but no start) ...... I have started reluctant V8's by removing the HT leads for cyls 1 2 7 8 this makes for a better spark at the remaining cyls
If there is a spark and plugs smell of fuel is the choke working? If HIF carbs then elec choke and problems likely. Remove air intake elbows and part cover inlets with something and try to start (take care!)
If it starts then switch off and check choke electrics ........ start at water temp sender. Does the water temp gauge work?
Obviously only get involved with HT circuits and fuel if you are familiar with these things..........A sorted V8 should be very reliable ............ and I'd be surprised if converting disco to diesel is worth the bother.
Good luck
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Hey guys really appreciating how much feedback im getting, finding it all really helpful!
http://cgi.ebay.co.uk/SU-Carburettor-linkage-Land-Range-Rover-P5-P6-Kitcar-MG-/170553019110?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item27b5c08ae6
It is these exact carbs that are on it and they have a wierd electric choke that i dont really understand and im not sure if it is wired up properly so the problem could well be the electric choke.
Ive tried getting someone to start it while i half covered the air inlets with my hands bit that didnt work either!
i should surely be able to see fuel coming through the needles even if the choke isnt working?? (sorry if thats a stupid question!)
I was just thinking the diesel idea cos ive heard if you have the conversion parts, putting an isuzu 2.8 diesel in them can be a good move and my mum had the same engine in her frontera and it was ace! (shame the rest of the car was pants)
Just realised that that link is for the linkages but like i said, exact same carbs, choke and filters ect.
Please dont give up on me!!
Cheers
Ally Tannock
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if it was a carb at fault would it not run on 4 cylinders?
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Still unclear as to whether the plugs are getting wet? If yes then there is a spark problem, a timing problem or a compression problem.
If no, then there is something wrong with the carbs. The engine should still fire, or at least try to, even without the choke.
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is the manifold tight to the heads?
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I was just thinking the diesel idea cos ive heard if you have the conversion parts, putting an isuzu 2.8 diesel in them can be a good move and my mum had the same engine in her frontera and it was ace! (shame the rest of the car was pants)
Let me think. Spend a couple of hours thinking logically about where the fuel is actually going (or not going) or spend a number of days and lots of cash converting to something that smells like a lorry and sound rubbish. Difficult choice, I think not!
Problem is not the engine or fuel type, just the fact that something is not quite right. Ever tried getting a broken diesel to work?
Hope the light-bulb illuminates above your head and you get it sussed. :)
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Hey again!
Manifold is tight to the heads.
Ill check the sparks tomorrow morning and see if there is fuel getting through. Ive had them out before but they were very black so i gave them a clean up and im definately getting a spark.
Like i said, im certain its a carb problem.
I did have it running on 4 cylinders (driver side) for a bit when it started to go wrong and then that stopped too and now im in the sorry state i am now!
Cheers again
Ally
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I know you have checked the timing, but how did you do it? Just look at timing marks? I had a V8 jump one sprocket on the timing chain because tensioner had retired. Check valves are actually both closed when at TDC on no1 cylinder.
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If there is fuel passing unburnt through the engine there should be a smell of petrol at the exhaust pipe.
Do you have oil in the dampers of the SUs? If not the pistons will be clattering up and down.
What makes you so sure there is no fuel at the needles?
There needs to be an airflow through the venturi of the carb for fuel to be drawn up through the jets.
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The timing hasnt been altered since it was running and when i checked the plugs i made sure i did them one at a time just to make sure i didnt get the leads mixed up so thats why i dont think its the timing but i could be wrong. And pardon my ignorance but i dont understand what you are saying when you said "check the valves are closed when at TDC on number 1 cylinder", do you mean the valves in the carbs or elsewhere?
The reason i dont think there is fuel getting through the carbs is because when it first started to do this, if i took the air filters off and poured fuel through the carbs down into the block it would start but only run on 4 cylinders like i mentioned above and when it did this i could see the carb barrels floating and fuel getting sucked up from the needle, now i cant see that at all. The carb barrels just flutter up and down about 2 mm when i turn it over.
The distributer bolt is also loose and it can rotate which i know is not helping matters but it has been running like that, could this be the root of the problem?
There is definately oil in the pots of the su's, i took them apart recently to check if there was something stuck in the intector but it was clean and i put fresh oil in them when i put them back on the car.
This is a pretty steep learning curve for me, ive mostly just done breaks, hubs, altenators ect till now, never anything engine based so i feel a little out of my depth!
I was intending on having another look this morn but suprise suprise its pissing down! Ill have a look if it clears up later on.
Thanks again
Ally
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Ah................
I think before you go any further the timing needs to be set from first principles.
The loose dizzy explains many symptoms.
The position of the dizzy is critical to fractions of a mm and the timing will have to be set statically to start the engine and then dynamically with a stroboscope to get the timing at full advance correct.
Then any fuel problems can be addressed.
The procedure is perhaps too complex to explain in a forum and I think you need to find someone who is familiar with V8s to peer under the bonnet.
I'm sure once you find someone in your area you'll be on the road again soon enough.
Good luck!!
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Hey
Right, cheers for that, ill look into it.
Might have someone coming up next weekend to have a gander but until then ill keep trying.
Realistically could i do that myself or should i just get it to a garage who knows what they are doing and get them to do it?
Thanks to all who have left comments, its been really helpful!
Ally
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Ally, the simple explanation of what we are all saying is that there are various mechanical adjustments that can be made in the engine. They are simple once you know what they are, and where they are. A bit like working on brakes - if you turn the adjuster the wrong way, the brakes don't work. Some of the adjustments are tiny but critical. Any reasonable mechanic can work through them and check/reset them - just takes time. Once that is confirmed correct is the time to start looking for oddities, but just getting these adjustments right will probably get it running again.
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Is there any possibility that the fuel supply and return pipes/connections have become crossed?
Geoff
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Ok
Ive pretty much come to the conclusion that this problem is beyond my mechanical skills!
I'm speaking to rangerovering about coming to take a look at it for me and failing that its going to a garage because it is in too good nick to ignore!
Thanks again to everyone who has helped out, ill let you know how it goes.
Cheers again
Ally
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Right, back again.
"rangerovering" and i spent most of the afternoon trying to get it running, it came closer than it has in ages but it still wont run.
The carbs have been switched back to the strombergs that were on it (altough refitting the throttle linkages seems almost impossible)
The timing has been re-set
The plugs have been checked and they are not the recommended ones but they are still ok and are sparking
The ignition coil has been switched to a better one.
Anyone have anymore ideas?
"rangerovering" might have a bit more to add!
Cheers again
Ally
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Ally,
sorry read your posts but hadnt read the first bit.
If you are still stuck & need someone local there is
'The Land Rover Doctor' Martin beside Loch Side Farm.
'some degree of cheapness possibly'
;)I would just get 'Jim' up from 'MoTech' to look for you,
Its the price of a call out but he will tell you in just a few minutes.
Or go into Charles Butlers behind Farm Foods, If you are not too far away
Geoff or Gav ight come out & have a looky for you without great expense.
Probably the best & cheapest option.
please call in to see them tho, dont phone.
Sorry not at home at present so cant have a looky, probably would be no further on than you
other than i would have changed the fuel for fresh petrol,
&
I would have started with new or 'perfect plugs'
are the plugs absolutly perfect,
each gap
& none cross threaded (NGK BP6ES or Bosch super plus,
what Gap do you have 0.8mm ??)
Are you sure of the leads coming out of the dizzy cap & the firing order?
Is the cap perfect & the rotor arm?
have you checked each thing your self & trusted nobody elses word.
Coil earthed OK?
You appear to have done a very splatter gun approach to finding the fault & several things can now be wrong.
I would change the fuel now,before doing more, thats a safe thing to do.
good luck.
george
PS are you turning it over with a battery with lots of cranking power? not just some jump leads fitted.
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balast resistor
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Is "ballast resistor" the cause or a suggestion?
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balast resistor
Its electronic ignition like all V8s from the early 80's onwards.
Started out checking for spark, which it had albeit weak. Then checked timing which I got to within firing tolereances (or so I thought!). Tried it and no joy.
Fiddled with the SU's for a while, tried a trickle of petrol in each intake and got a couple of coughs. Problem still seemed to be fuel related.
Rather than mess around with SU's which I know very little about, we refitted the previously perfectly functioning strombergs. The throttle linkages had been removed and it was a difficult one to fathom out how they went back together.
Put the fuel feeds and returns on and gave it another go. Bit more coughing this time but still no fire. Put the timign light on but couldn't get it to strobe. Eventually traced it to a naff pattern part coil. Put another better brand on and we had a strong spark again, but still no fire.
By this time the daylight was going and it was getting more and more frustrating! I have a feeling the timing is still not right, even though rotating the dizzy had little or no effect. Thats said there is still a problem with getting the right amount of fuel in.
cheers
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ballast resistor increases the power of the spark when cranking
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Cheers for that steve.
Im going to try a few more things that have been suggested (change to more appropriate plugs, apparently the ones that are in are not best suited to the engine) but failing that ive contacted Armson Automotive Engineers to see if he can have a look next time he is up this way.
Suggestions still welcome, im not giving up on this!
Cheers
Ally
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I would recommend a email to bobtail phil he had this problem with 3.5. it might help
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Surely it's the lack of a ballast resistor in series with the coil which increases the coil voltage when cranking. But if it is open circuit then when the ignition switch comes back off of "cranking" there is no current through the coil and no sparks at the plugs.
That all said, if electronic ignition is fitted is there still a ballast resistor?
Are the valves opening and closing?
Sandy.
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I now own this car - engines going in my 90 - sorry for long winded reply but it might help someone else in future given this is the first thread that comes up when you google "3.5 rover v8 wont start"
Wen i bought it it would fire of sorts - had to hold the key round for ages to get engine up to speed and once going would backfire under load and stall if you tried to drive it.
I first took off the electronic choked carbs as it had a bit of pipe jammed int he back of it and didnt seem to do owt at all and engine ran like shite cold
I fitted a set of manual chokes that came on an engine i got off bob on here which i wanted the gear box from
Manual choke on , she didnt fire at all , getting worried id screwed it up totally at this point. But it has been sitting for 4 months since i last had it firing even roughly
Worked round the engine cleaned up the dizzy cap , checked the timing , checked resistance of leads , cleaned up the sparkplugs - checked for spark , nada
Bought new spark plugs , fitted and checked no1 against the body agan , got a single spark despite starter turning fast.
Checked the coil inputs , it was getting a single 12v input and 10v output when the key was round , and cutting power when the key came back to running position. -
Wired it up to what i thought would give me a perminant 12 in and 10v output
Pulled the plug and earthed out , turned the key ( no choke t this point and its -4 outside) and got a bright blue light show of repeated sparks and the engine roared into life , killed it , stuck the plug back in , pulled the choke out , turned key and first turn it roared into life just as bobs trialer did at his yard .i never thought id get this engine to run like that. , once warm revs freely no backfiring. Shes a little bit smokey but shes been sat for nigh on 3 years i think and running like crap any time she has been running in that time.
Project v8 90 is back on after spending so long getting this bugger running !
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And to be fair to ali and rangerovering the discos wiring is a bloody mess , and now i have it working when it goes in my 90 ill be rewiring it to be much neater and safer.
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And to be fair to ali and rangerovering the discos wiring is a bloody mess , and now i have it working when it goes in my 90 ill be rewiring it to be much neater and safer.
Good plan, I tried to get it goign before and the wiring was indeed interesting!
The original problem was fuel pressure, couldnt fill the carbs up it was that pathetic. They did get it started but dont think it ran for long on a coke can lol Hope you get some good running out it now 8)
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The facet external pump spits fuel over the bonnet with no problems at all , was that on when you had a go or was it still the in tank pump ?
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I really don't know dude Stu from Armson AE did it but I wasn't with him at the time.
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It was that pump that was the problem, it was new and it was running using that pump to begin with but then the problems at the start of this thread began. In the end Stuart took it off, beat it with a hammer and that seemed to sort it. Classic bit of engineering.
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Stu said it was a good engine when he had it going. Said it sounded smooth and that the cam sounded ok too.
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Are the dash pots filled with oil, unscrew the top of each carb and check needles move up and down easily.
Cheers and good luck. You can't beat the the sound of a v8.
Charlie