Nissan (Un-modfd) v-6 problems

[Jack Thompson]

Have a 90 Maxima with v-6 that is pretty much the same engine that they have used up to now. 2.5liter in this case. I have been runnng up to about 50+% E85 until I started to have some engine problems. I replaced sparkplugs, distibutor and wires, coil packs and fuel filter. The car still runs very rough at idle a bit better around 3000 rpm. One mechanic says that the ethanol has ruined something in the fuel system, maybe the fuel pump... Does this sound familiar to anyone that has an unmodified car or modified for that matter?

[Erik Weaver]

Well, I am far from the best one to respond. But it seems like most people report that is what they are told. Even when it is not true. You are doing the right thing by checking into this more deeply.

So are you saying that after using the ethanol blend and going back to straight Arab oil you are still having this trouble?

Ethanol has a cleaning effect upon the gunk that gasoline leaves behind. It is possible some of that has clogged something. I'd double check there are no additional fuel filters hidden away. It seems like the trend has moved to hiding these things, unlike the old days when you could just pop the hood and change them.

Also, the ethanol while in the fuel will effect your timing -- or more exactly it requires the timing to be adjusted in order to fire at the optimal timing interval.

AND, many cars with "computers" in them "see" the pattern of the results of burning a "too clean to be possible" fuel (ethanol). Then the computer starts trying to "fix" that problem. So you'll also need to know if there is a "computer chip" in your car that reads your fuel mixture/exhaust/etc.

How long did your car run before the troubles showed up?

In what way did you step up to the 50/50 mix of Arab oil/E85-ethanol?

In the meantime, hopefully one of the "gear heads" will check in. This is not an area I know much about.

[Sodbuster]

Hi Jack,

Erik has given you some good info, here is my 2 cents.

Ok first of all your mechanic has very little knowledge on fuel, it is far more harmful to any ingine to run it on pump gas than Ethanol. Pump gas burns nasty, dirty, filthy and will flat out destroy any motor in time, this is why the average life of any motor is drastically reduced when it is ran on pump gas. In most cases 150,000.00 and the motor is history if your lucky and did regular oil changes, now a motor on Ethanol can and will double the life if not triple.

Ok so forget mechanic A and lets try to come up with a logical explanation to what has happen.
First you need to check the pressure coming out of the fuel pump, if mechanic A did not check it how can he come to a conclusion that the pump is history. Lets just say the pressure comming from the pump is 50 psi (just a example)
but the " minimum" that the repair manual calls for is 55 psi that means you are 5 psi short and this can make your vehicle fall flat on its face on acceleration or have a very nervous Idle and this is a very typical problem.

If the fuel pump is history it had absolutely nothing to do with Ethanol/E85. Pump gas is the culprit to any fuel delivery problem, pump gas will varnish, go stale, contaminate and finally gum up your fuel system in time and most likely the E85 that you introduced to your vehicle has cleaned up the trash and this was bond to happen no matter what.

When we run Ethanol we are running basically a solvent, alcohol is a cleaner and will never go stale, or varnish up, or foul and contaminate. Ethanol burns clean and we do not need to run additives like fuel system cleaner`s or sea foam or STP or any fuel system cleaner that will only cost more money.

Ok so ditch the Idea that Ethanol has destroyed the fuel pump, never happen!

Another important thing that absolutely has to happen is do we have compression in all 6 cylinders? time to do a compression test, if we have a cylinder say less than say 110 PSI that cylinder will never fire and you can throw new parts all day long at this motor but unless we have compression you are going to have a motor that will have a bad Idle ( nerves so to speak).

Run a compression test on all 6 cylinders just so we no were were at, and if all cylinders are up on compression than we can move on to the next level. Look for a compression test of 150 psi per cylinder or so, it can be less but remember we need at least 110 psi to fire that cylinder any less is a dead hole.

Hope this helps, there are some mechanics on this forum that I'm sure can chime in. Don't get discouraged and chime back in and let us no what you have found. Good luck!

[The Future]

Arabs own alll oil?

[HAIN KANA]

One simple way is to find out if you have any weak cylinder.You can do this by pulling back one spark plug wire at a time while the engine is idling.Also wiggle the connector for the fuel injector see if it response they could have corrosion on the connector.if all seems to be responding well then do a good fuel injection system flush ( preferrably with a machine) not from a bottle canister.Hope this will help you