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350matt, Engineer
Category: Mitsubishi
Satisfied Customers: 21605
Experience:  Mechanical Engineer BEng Hons 22 years experience in car engine industry, 10 years in formula 1
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I have a 1997 mitsubishi lancer ck2 using a DOHC 4G15

Customer Question

Hello, I have a 1997 mitsubishi lancer ck2 using a DOHC 4G15 engine. The car had been behaving strangely in that it looses power when you rev upwards of 3000rpm while driving and it just dies out (producing something like a breaking effect) making it extremely difficult to drive at high speeds as it is difficult to overtake especially uphill and the car can't run to speeds above 100km/h. Furthermore the car was generally weak and really labored on the road. I went to my local mechanic where he did a series of tests on the electrical system and found the alternator to be overcharging (was producing 17v at idling) the battery was also dry with all the electrolyte poured out. I bought a new alternator which I replaced with the old alternator, also bought 2lts of battery water and topped up my battery and everything seemed ok. for the first 100kms as the car ran perfectly, good take off speed, and good engine power. However, yesterday I went for a 200km long trip but after covering about 150kms the car started the initial problems where it lost power at high revs completely cutting off the acceleration. When I tried pushing it harder I couldn't make to speeds above 100km/h without the car jerking and being unable to hold at a rev of about 3000rpm. however, maintaining revs of 2500rpm the car runs without jerking although you can feel the car is not very powerful as I can't go over hills easily. I checked the battery and it is not overheating and the electrolyte is at the max level that I had put it. I have also measured the voltage out of the alternator and it is steady at 13.8 at idle (about 700rpms). This is really stressing me out and even my local mechanic can't think of a solution. Do you have any suggestions? Please help me
JA: Is the power loss consistent, or does it fluctuate?
Customer: no it flactuates, but very evident while going uphill when in need of high revs
JA: Are you fixing your Lancer yourself? What have you tried so far?
Customer: Not myself but my local mechanic is very engaging and normally explains things pretty well before doing anything. We havn't done anything yet as everything seems to be fine
JA: Anything else you want the mechanic to know before I connect you?
Customer: Not really, I have basically given all the information
Submitted: 9 months ago.
Category: Mitsubishi
Expert:  350matt replied 9 months ago.


This sounds like a lack of fuel and could be a lack of fuel pressure from the electrical pump at the tank.

1st thing to try is to remove the fuel filler cap and then flick the ignition on whilst listening for the brief ‘buzz’ of the pump

If the connections to the pump are corroded or damaged then the pump could stop at any time or could not be running at full speed. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,

Ideally measure the pressure at the injector rail (should usually be around 3Bar / 45psi +) and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure.

You can also get this issue with contaminated fuel , if there’s water or dirt in the tank then either the petrol floats on top of the water or the filter sock on the pump is choked up – so if the other things check out then I’d consider pulling out the fuel pump and cleaning the filter sock