Mitsubishi Magna help

Submitted: Monday, Feb 20, 2012 at 18:57
ThreadID: 91988 Views:3660 Replies:7 FollowUps:3
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Hi all, this is one for the mechanically minded. Please read carefully.

I will do my best to describe the problem.

The car is a 1995 Mitsubishi Magna TS 2.6L carb model sedan, 5sp manual with 378,000km.

When the engine is cold (i.e. within 5min of initial start-up), and under light to moderate acceleration, the car will start to severely kangaroo-jump usually around 70-80km/h in top gear. It will do this in lower gears and speeds as well. Normally to temporarily overcome this problem, I would push the clutch pedal in, let the engine recover (it will usually climb to 2,500 RPM), pump the accelerator a couple of times and then resume driving. This process can repeat a few times in a short period. Actually it will do this *sometimes* even when the engine is warm (not hot), but more when it is cold. However, when the engine is hot and when driving on flat roads, even under heavy acceleration, the engine performs flawlessly. BTW, I have confirmed that the choke valve opens when the engine is warming up in the driveway.

Then the other side of the saga is this. When climbing a very steep (20% gradient) road, the car again will start badly kangaroo-jumping and then completely die. But the strange thing is, is that I can restart the engine normally. That is, the engine will start immediately without pumping the accelerator. Now, this is all happening when the engine is hot and the choke is open.

In January we decided to get the engine rebuilt because it was getting tired and I mentioned to the mechanic that I suspect this particular problem is carburettor related and I asked if he could look at it. Well, he got the engine rebuilt fine but admitted he did not look a the carb. I wasn't amused. And after having to fix a couple of other things after him, I have decided not to entrust the car to him again. So I'm trying to get this problem solved on my own or going to somebody else. I do have moderate mechanical experience so I'm not a complete dumbass =) but this problem really has me beat. I am suspecting the carb. float/needle valve. I have repaired carbs before on older vehicles, but have never encountered this problem.

I replaced the fuel pump just under two years ago, so I don't think this is the cause. I also blew out the fuel lines/return lines and installed a new fuel filter. The air filter is also still serviceable. All the vacuum hoses are currently connected properly in their particular order. Actually I had to correct the hoses because the mechanic muddled them up when reassembling the engine. The result was that the air conditioner idle-up was not working. I had to follow diagrams in my service and repair manual to re-route the hoses and fix the problem.

So, after spending $4000 I have a virtually new engine (which I am pleased with), but still the same old problem which is not getting better.

I hope this makes sense. I don't think I have left anything out.

Any help will be greatly appreciated.

Thanks, Tim.
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Reply By: IronMan - Monday, Feb 20, 2012 at 19:09

Monday, Feb 20, 2012 at 19:09
A long time ago in a galaxy far, far away, I had a TM Magna Elite with the 2.6 Carby engine. Until my current Verada, that Magna was the best car I have ever owned, bar none. I traded it for something that will remain nameless, but was built at Broadmeadows. Quite likely the worst automotive decision I have ever made, or ever will.

Although mine was an auto, I also had issues with surging. The carby on the Magnas was an ingenious thing which worked wonderfully to provide adequate fuel at all throttle openings while conforming to all the relevant pollution laws of the day. While it was new. After a few hundred thousand kilometres, the various mechanisms, valves, diaphragms, and tiny passageways start to block up with a varnish like substance, limiting the function of the mechanical marvel. To this day I wish I had just thrown mine away and bolted on a fuel injection system from a wrecked model (quoted $2200 fitted in 1995).

Firstly, take it to a specialist carby rebuilder. Or find a good mechanic who will fit injection, or buy a KF Verada.
AnswerID: 478241

Follow Up By: Mudripper - Monday, Feb 20, 2012 at 20:47

Monday, Feb 20, 2012 at 20:47
Thanks for the reply.

I agree, the Magna's were and still are a great car, and were technologically advanced well before their time.

I strongly believe that it was the mechanic's responsibility to ensure that the carb was cleaned out and serviced before going back into service. Especially after I asked him to look at it.

I think finding a 'good mechanic' nowadays is a hopeless task! Nevertheless, I will try to find somebody that will hopefully do the job, possibly what you mentioned. I am also thinking of going to the closest Mitsubishi dealer.


FollowupID: 753757

Reply By: 120scruiser (NSW) - Monday, Feb 20, 2012 at 21:18

Monday, Feb 20, 2012 at 21:18
Agree with Ironman
Carby overhaul or new will fix it.
AnswerID: 478262

Reply By: Bushranger1 - Monday, Feb 20, 2012 at 21:21

Monday, Feb 20, 2012 at 21:21
G'day Tim,
I had a Subaru some years back with the same symptoms. It had a carby with a sight glass & noticed that if I shut off the engine immediatly the symptoms appeared, the fuel level in the glass would be low.
It drove me nuts trying to fault find it. Eventually found a second fuel filter at the tank that was partially blocked. Changed that one too & bingo problem solved.
AnswerID: 478263

Reply By: Muntoo - Monday, Feb 20, 2012 at 22:35

Monday, Feb 20, 2012 at 22:35
I think the 1st problem is that you spent $4k on a vehicle that aint worth half that amount.

Could be the carby.

Unbolt it and give it a general clean and inspection.

DO NOT take it a Mistubishi dealer.

Take it to a proper carby mob, or engine rebuilder.

All the guys in Mistubishi dealership will be younger then the car and never worked on one before. Probably think a "carby" is the oppposite to a "fourby".
AnswerID: 478278

Reply By: garryk - Tuesday, Feb 21, 2012 at 14:28

Tuesday, Feb 21, 2012 at 14:28
I had to rectify a similar issue many years ago and it was the float that was the cause ; over the years it had become porous and had absorbed fuel making it heavier than it should be and was impossible to set float level to deal with all throttle openings from idle to flat out'

AnswerID: 478318

Reply By: Member - G.T. - Tuesday, Feb 21, 2012 at 18:01

Tuesday, Feb 21, 2012 at 18:01
Check to see that the needle & seat in the carburettor is not sticking. It can stick in the closed position, subsequently starving the carburettor for fuel. It then can come`unstuck,` let an amount of fuel through & it will go again briefly until the fuel is used up and the the motor will cut out because there is no fuel left, as the needle & seat has stuck up again. I`m not sure why the engine temperature has a bearing on your problem. I had this problem years ago on another vehicle, took me ages to find it. Regards G.T.
AnswerID: 478341

Follow Up By: Mudripper - Tuesday, Feb 21, 2012 at 20:23

Tuesday, Feb 21, 2012 at 20:23
Thanks G.T. for your reply. Yes I think your theory pretty much confirms mine.

Definitely time to strip the carb.

FollowupID: 753850

Reply By: brad1972 - Tuesday, Feb 21, 2012 at 19:53

Tuesday, Feb 21, 2012 at 19:53
Does this have a coolant hose going to it to control the choke? could be worth a try, it would explain the temp change.
AnswerID: 478353

Follow Up By: Mudripper - Tuesday, Feb 21, 2012 at 20:26

Tuesday, Feb 21, 2012 at 20:26
Yeah it does have coolant controlling the choke. There may be a blockage somewhere or perhaps corrosion.

I will surely find out in the end!

Thanks for the reply.

FollowupID: 753851

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