Can't get it running... What's the best thing to do

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mordzy

mordzy

Active Member
Posts
308
I was considering writing off my 3.9v8 engine(truck was bought as unfinished project) as after days of trying I can't get it running for more than 5 seconds.

Carbs have been serviced. New coil, electric dizzy, leads. Malpazzi fule filter/reg set at 2.5 bar. Can occasionally get her to fire but sounds like a bag of spinners for 5 seconds before it stalls.

I have taken off the rocker covers and it's full of carbon dust and no sign of oil. Though after speaking to my dad he tells me the oil pump probably won't get pressure to chuck the oil up. And after cranking her over for days trying to start this May have dried it out? Thoughts?.

I continued testing with the covers of and there was a lot of exhaust fumes coming in to the crank case either side which I'm not sure if is normal.

So I don't know what's best to do next. Oil pump could be knackered.. But even so what's the best rout to go down? Check pump to try get her running?

I have swapped sparks plugs round, checked timing is all ok and TDC is ok to when first piston fires. When it does catch and run it runs like it's either not firing on all cylinders or something.

Pervious owner got it through the mot but had a carb issue which I fixed with a carb service kit.

Any suggestions?
 
Definitely compression check if gasses getting into the sump!
Oil pump should be able to pump oil up to rockers while spinning over, even if its not fully up to pressure, is there enough oil in it! sounds a dumb question but hey have fixed peoples motors before that were almost dry!
 
When I had fuel pressure issue I dropped oil and changed filter as I had petrol in sump.

I put 5 litre in, waited an hour and checked dip stick. Was mid way up.

Have ordered compression gauge
 
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Has the oil pump been off/changed?

If so was it packed with grease to allow it to prime?

Is it on lpg?

Sack of knackers and not running could be burnt out piston rings or valves.

As suggested cet it comp tested.

Is the timing set and have you checked it?
 
Following on from last post on your other thread and having gone through a similar thing recently with my rare 4.4 aussie rv8 I would say do the basics (it sounds like you have done most of them) and a compression test as others have said (also tripple check the timings not 1 tooth out and its getting fuel then try moving the dizzy side to side while a mate cranks it over as this can get the tired motors to fire)

if you do pull it out to swap it there is no reason not to strip if before buying another and check condition, mine seemed like it would have been fine and did run apparently but when I stripped all the bearings including the cam bearings were down to the copper as the oil had not been kept up to scratch and one head was cracked in the 3 places. the bores had no lip at the top so seemed good but were actually all over the place lower down and had to be re-done and new pistons (going in this week I hope).

What I am saying in a rather long winded way is that yours maybe ok for a freshened up with some new rings and shells but you wont know till you look inside :)

NB: if the lifters are dry the compression test can give enronius readings as the lifters and not fully pumped and do not open the valves all the way, mine tested really well but then I found what I did inside, mind you it was probably as healthy as my old 3.9 and I ran that for two years, it was a dog and would use a liter of oil every 200 miles on the motorway with no smoke pmsl round town it used none though lol
 
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Thanks for the help guys. As I say;

No LPG just petrol
I have not taken the oil pump off
I'll check timing again
Will compression test at weekend

I did the cranking and turning the dizzy last week which got it started. Thing is it won't start again. We achieved it maybe 3 times in one day thinking it was that, then perhaps the ignition, then perhaps the plugs...

I think returning the carbs to datum might help. Trouble is, it's my first project so I'm way over my head. But that's part of the fun.

I think ill do m10 bar oil pump on a battery drill and compression before I try start it again..
 
mordzy said:
Thanks for the help guys. As I say;

No LPG just petrol
I have not taken the oil pump off
I'll check timing again
Will compression test at weekend

I did the cranking and turning the dizzy last week which got it started. Thing is it won't start again. We achieved it maybe 3 times in one day thinking it was that, then perhaps the ignition, then perhaps the plugs...

I think returning the carbs to datum might help. Trouble is, it's my first project so I'm way over my head. But that's part of the fun.

I think ill do m10 bar oil pump on a battery drill and compression before I try start it again..
Click to expand...

Where are you? Somebody local might be able to help.
Too much wiessbier and meds tonight.

has it ever been on lpg?
 
You say it's a 3.9 on carbs... why?
Did you do the work?
Has the setup been checked thoroughly?

Is the dizzy in correctly, sounds like timing is well out...
 
Came like that. The guy who put it together took the 3.9 out of a rr classic and put some SU carbs on. He got it through the mot but was running rich. I have put a service kit on the carbs and a pressure reg.

I take it your saying there's an issue with carbs on a 3.9.

I'm based in bradford.
 
mordzy said:
Came like that. The guy who put it together took the 3.9 out of a rr classic and put some SU carbs on. He got it through the mot but was running rich. I have put a service kit on the carbs and a pressure reg.

I take it your saying there's an issue with carbs on a 3.9.

I'm based in bradford.
Click to expand...

Sorry, reply was deleted... :mad:

No problem AFAIK with carbs on a 3.9 , just wondered if there was a reason for it other than the carb v efi thing. :)

Have you checked the engine is set up reyt r.e. carbs, timing, oil pressure, electrics and compression?

I'm in Barnsley but it's a bit far to come to bratford to have a look at summat I only half (Carbs...) know about.

I still think the sack of spanners job sounds like the timing's out...

When was it last running properly?

:)
 
Yeh you could be right. Like I say, I'll do one think at at time to eliminate.

I could also use the timing gun to make sure each cyl is firing. I did spot an odd wiring setup on the fule pump. Neg was bolted to the chassis and the pos to the neg of the coil... It worked but I've moved it as it didn't make any sense.

Was last running 10 months ago for mot but I didn't see it. So I have to take it with a pinch of salt.

I'll see if I can get hold of the guy I bought it off but can't see what's changed since the mot. It's just been sat.

FYI the coil and dizzy is new. One of them powerspark kits (not fitted by me)
 
mordzy said:
Yeh you could be right. Like I say, I'll do one think at at time to eliminate.

I could also use the timing gun to make sure each cyl is firing. I did spot an odd wiring setup on the fule pump. Neg was bolted to the chassis and the pos to the neg of the coil... It worked but I've moved it as it didn't make any sense.

Was last running 10 months ago for mot but I didn't see it. So I have to take it with a pinch of salt.

I'll see if I can get hold of the guy I bought it off but can't see what's changed since the mot. It's just been sat.

FYI the coil and dizzy is new. One of them powerspark kits (not fitted by me)
Click to expand...

Best bet will be to go through it and start with the basics, I only had mine about 18 months but I think I had most of the usual problems barring HGF... :rolleyes:

Stick with it, there are a lot on here with more experience than me just don't ask drivel! :p:p:p:p:p:p :D:D:D:D:D:D:D:D
 
su carbs..2.5 bar pressure!!?? you sure??thats fuel injection high.. you will flood the poor engine cos its just forced the fuel past every hole in the carb..su can be gravity fed,or in a car maybe 4-6psi max...not 37psi!
 
su are only supposed to be 2-3 psi which I know sounds low but only a mechanical pump originally then a facet tap tap

I just thought he had got his psi and bar mixed up :p
 
zen said:
su carbs..2.5 bar pressure!!?? you sure??thats fuel injection high.. you will flood the poor engine cos its just forced the fuel past every hole in the carb..su can be gravity fed,or in a car maybe 4-6psi max...not 37psi!
Click to expand...

Sorry I mean psi.

I did grav feed it from the fule tank out of my lawn mower. Before I got a decent filter/reg
 
Not sure what you have done but this is what i would do (some mentioned before)

1st prime the oil with a drill.
you should see atleast some oil come to the top.

then get it to TDC on number 1 cylinder (check the inlet valve for no1 has just closed before getting to TDC) then get the distributor set up with the rotor over the no1 ht point (helps to mark with a marker on the dizy body)
then advance it 6deg. and test with a timing gun.

then if it still isnt working do a comp test and then look at replacing parts like leads, plugs ect
 
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