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4.0 Cleaning Fuel Injectors


H munster

Well-Known Member
U.S. Military - Veteran
Joined
Mar 21, 2008
Messages
132
Age
56
Vehicle Year
1984 Bronco II
Transmission
Manual
Is it possible to clean fuel injectors or do they have to be replaced? Im not getting gas to #6 but i can hear the injector clicking which leads me to believe it is plugged.
 
I know they can check the injectors. You will most certainly have to pull the injector out anyways. If you have a seperate vehicle you can take the injector to a mechanic, have them check it, and if they can clean it then sweet, if not, then there goes more $$$. also remember to be careful with the injector seals. I learned the hardway...
 
you can try having the injectors clean in the vehicle (takes a special peice of equipment to do), but its not a guaranteed fix.
 
I had mine sent off to a place that flowtested them, sent me a chart of the flows. Then cleaned, and rebuilt them. Sent me a second chart of the flows and mailed them back to me.

It all cost less than $60.
 
I had mine sent off to a place that flowtested them, sent me a chart of the flows. Then cleaned, and rebuilt them. Sent me a second chart of the flows and mailed them back to me.

It all cost less than $60.
do you remember who?
 
Cleaning injectors is a crap shoot.....they could end up outlasting the truck or their coils could end up with shorted windings in the future and whatever money you put down is gone.



BTW, how do you know you're not getting gas to a cylinder? A lean condition in one cylinder can be an intake manifold leak (which is common on 4.0's)
 
I don't know that I have a problem with the injectors, but I have the heads off the truck and I figure there is no better time than the present.
 
If it ain't broke, don't fix it.

Seriously.

If you find a plugged injector 100,000 miles from now, it's a HECK of a lot less work to pull it out than it was the heads.

Unless you put contaminated fuel in your tank AND it somehow gets past the filter, your injectors will easily outlast the rest of the vehicle.

If you want to set your mind at rest, drop the tank and see what is in the bottom. Odds are, it's nothing.

I'd give this a wash as to whether it's worth it to replace the injector O-rings. Only because on 4.0Ls, it can be rather easy to cut them on installation.
 
a well known machine shop here in WA uses simple green, it works 100% better than the crap at auto stores, they sware by it.
 
Injector O-rings should be replaced if they are removed from the fuel rail in my opinion.
Most shops do a fuel injector flush/cleaning, and dump the cleaner in a vacuum line. I witnessed this once and asked "how the hell is that reaching the injector?". They didn't have a good answer. WTF?
If you know one is bad, and you have everything apart it's best you have them "rebuilt" or just replace them.
Injector flushing should be regular maintenance, even along with a filter change. This will ensure long life out of the injectors. It does require a special "tool". The fuel line is disconnected. A canister is connected to the fuel rail. You place your cleaner in the canister and attach an air hose to it. It has a regulator so you can set the pressure to simulate a vehicles fuel line pressure. You run the vehicle on the cleaner while it cleans the injectors.
It'll be unlikely that a shop will have a flow tester. The cost $$$$$. Most likely if you want them flow tested they'll have to be sent off.
 
Leave them alone. I've never cleaned an injector or poured anything into the fuel tank except fuel stabilzer in something that sits all winter. If you think one injector is bad I would maybe have that one tested only. I would be inclined to look very hard elsewhere for the problem though.
 
http://www.cruzinperformance.com/fuelinj.html

When they did the flow test on mine some of them were just trickling and some were pouring.

I had them cleaned because I was having a "hard start" issue that only happened when warm. It turned out to be a bad FPR, and to be honest I didn't notice any difference after the cleaning. Other than a lighter wallet and a hope that they are better now than before.
 
Changed plugs about a month ago. Cleaned MAF sensor and after that i noticed a miss. Pulled plugs and 5 look used as normal. # 6 looks brand new like it had never fired. Did normal elec checks and i got spark. Reinstalled plug and started engine. Removed plug and no gas or smell of gas. No oil no gas nothing. BTW that exh manifold is hot as hell at shut down. started it again and put a long extension on the injector and heard the clicking.
 
Sounds more like a DEFECTIVE injector than a plugged one. Like, it has NEVER been fired.

It's pretty hard to imagine a dirt-in-the-fuel problem that would completely hose up one injector and leave all the others fine.

Just buy another.... ONE other.
 

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