Injector Flush

[Jono]

Any tips on doing a flush on a '96 GT-40? I've never done it, and have a buddy who is an auto mechanic doing it for me.
What should the air pressure regulator be set at?
Should I be disconnecting the fuel pump? How?
Any other standard procedures?


Thanks for any advice.

[DanielC]

I have a 1997 ski Nautique with 2258.4 hours on it. It has never had the injectors flushed. It is running fine, averaging about 3 gallons of fuel an hour.
In 1998, I had to take my 1996 Ford Aerostar in for some warrenty work on the brake light switch, and the service manager tried to sell me a "fuel injector cleaning" when the van had about 18,000 miles on it. I refused, and my van now has over 172,000 on it. I recently had to replace the head gaskets on it, and I Just gently cleaned the exterior of the fuel injectors when i was reassembling the engine, and put them back in.
Why the tangent? I honestly do not think fuel injectors need to be cleaned, or flushed near as often as people are told it need to be done. I believe the biggest reason fuel injectors get cleaned is to enhance the profit margin of the dealership doing it. You have to realize one of the best solvents for cleaning deposits on an engine is gasoline. There are fuel filters in the FCC to prevent any crud from ever getting to the injectors

That all being said, if you really have a legitimate need to have your fuel injectors flushed, I would think the same service procedures used for a mulitport fuel injected 5.8 Ford engine in a pickup would be close to the one to use.

[maxpower220]

+1. If you are using "good" gas, there should be no reason to clean the injectors. A poor running engine would be the only time that I would consider it. There are a few filters/devices to keep trash out of your injectors. No reason to think that they aren't working. If the boat was not winterized properly, bad (trashy) gas was put in, or the boat has sat for a long time would be conditions to consider doing a flush.

[Jono]

What got me to this point is when i changed my plugs and found I'm running lean. There was 1 plug that was brown, 2 that were light grey, and the rest a darker grey. Having these differences in colours made me think flushing the injectors would be a good place to start.
I'm on my second year owning this boat, and I don't know if the previous owner let the gas go bad. With only 400 hours on a 14 year old boat, I could see gas getting varnished up at some point.
What else would you check?
Some other possible causes for lean in my research were a leaking intake manifold, or poor cooling. How would I detect a leaking intake manifold?
As far as poor cooling goes... although I have a 160* thermostat, the motor seems to always run a little under - about 150*. It gets up to 160* at wakeboard speed, but drops when the load is lessened. I wasn't too concerned about this one, but should I?

[bobchris]

let him flush your injectors, the gas setting in the injector body alone gums stuff up regardsless of the grade or brand. You need to ohm the injector to find out if they are bad and need replaced.

[maxpower220]

Since you are having plugs with different looks, I would start with compression check on the engine. It's fairly easy and can be done quickly. It will be a starting point for the real health of your internal engine. All of the cylinders should be within 10% of each other and a minimum of 125 psi.

If the engine is running fine and you are just worried about the plugs, change the plugs run the boat for a month or so and check the new plugs. The summer is no time to be doing work on the boat, it's time to ski!

[Jono]

update -
I just ran lucas injector cleaner through 1 tank and the plugs are now perfect brown.
Sometimes things are easy!

[2gofaster]

One thing I've learned from my years in drag racing is that the plugs cannot be read accurately with even 10 seconds of idle time on them. Idling thorws everything off. Not to mention, color alone is not an indicator of mixture. Different gasoline additives will color the spark plug differently.

[Jono]

In motoX you're supposed to run the bike wide open, click into neutral and kill it. I know the reasoning. Do you do the same thing in a drag car? Would you do it in a boat?

[2gofaster]

In motoX you're supposed to run the bike wide open, click into neutral and kill it. I know the reasoning. Do you do the same thing in a drag car? Would you do it in a boat?

Yep, same applies in a drag car. Same in a boat.

[gride300]

can i do this on the trailer w/ throttle button pushed in?

[2gofaster]

can i do this on the trailer w/ throttle button pushed in?

No, you can't. With no load, the engine will be running in a different cell in the fueling and timing map than it would under power/load. Also, color of the ground strap and visible area of the electrone don't mean much when reading plugs. The fuel rings are FAR more of a telltale than color, due to the fuel additives in todays gasoline. You need to be able to look down inside the body of the plug at the electrode to read the fuel rings. If you have a sparkplug magnifier and can do this, you can see concentric rings around the electrode body. Where these rings are and their color are what's important. Color, where the fuel rings reach to on the electrode, and where the heat mark are on the groundstrap all tell you about the mixture.