The other day I noticed a whiff of fuel and after opening the hood, sure enough, I can see that injector #3 is wet after shut-down. I'm not sure if it's an O-ring or the injector itself that is leaking, but I have spare injectors and new O-rings so I'll replace both.

Just wondering how viable it is to replace the injector without removing the upper intake. It seems like #3 might actually be the easiest to R&R this way, but it might still be an exercise in futility.

Any thoughts or experiences?

 

Just in case anyone searches for this, indeed it is possible. In fact I replaced all 6 injectors tonight without removing anything but the fuel rail. Some patience is certainly required - if you have big mitts it might start to border on impossible rather than possible.

 

I have that big mitt problem and the intake design on these engines is just stupid. I want to change my injectors and it isn't going to happen anytime soon after my last run in with that intake and ending up repairing 90% of my 20 year old vacuum lines.

 

I honestly wouldn't have thought it possible to change them without taking off the intake. Had to be pretty frustrating.

I didn't think the upper intake was that bad to remove, only took me about a half hour or so the first time. Half of that time was messing with the egr tube fitting. I coated it with anti-seize and the next time I got the intake off in about 10 minutes when I pulled the engine.

I know you don't have to take the upper intake off to pull the engine, but considering the age of the wiring I figured I was better off not messing with the harness connector and it made reaching the fuel line connectors a lot easier.

 

It wasn't that bad, but you're right, I may not have saved anything time-wise as certainly it would have been quicker with the upper removed. My bigger concern was that I might trash the gasket in the process and I didn't have a spare on-hand.

BTW, the one thing I discovered is that the 4.9 injectors are the same as the ones used on the '91 - '93 2.3 Mustang, which is why I went ahead and swapped them all out (I had a couple sets of low-mileage pulls on the shelf). The references I'm finding say they're only shared with the '87 - '89 4.9 but I've seen them on several 90's 4.9's in the junkyard - part# F1ZE-B4Z and 9F593, as found on injector body. These are the later style injectors with the four spray holes vs. the earlier single pintle design.

 

What's your opinion on the 19 lb injectors? I've read where a lot of people with these trucks have switched to those.

 

You need a proper tune if you're going to increase injector size by that amount. Yes, I realize some people have done it without a tune but that's only because closed-loop operation has saved them from running fat-rich all the time. Instead, they end up only doing it some of the time. I guess if you like burning extra fuel for no reason it's a great idea?

 

I didn't know that tuning was that necessary in this case. Seems it's not worth the job if you have to do tuning.