Seth2w

So I have a 88 4.0 Renix and lately when I'm just crusing down the road anywhere from 35-65 mph the jeep will start acting like its not getting fuel. If I hit the gas hard its fine. I believe its the injectors and I want to upgrade to the 4 hole sprays but I would rather make sure what the issue is before spending money on something that may not fix the problem seeing how I'm on a limited budget. Any ideas or am I in the ball park with this one?

BTW new fuel filter on it. 2 months old

beefmobile

one way to figure out if one or more of your injectors are going bad is to get a Folgers can and pull each injector ONE BY ONE while your engine is running. pull it out and aim it into the can. your engine will start idling very badly, but you will be able to observer how your injectors are flowing. You can run injector cleaner or Mystery Oil or Seafoam through your gas tank to get a good cleaning. Those will do wonders.

This fits the budget criteria.

Seth2w

I have Seafoam before, the last time it was in the gas tank was right before I changed the fuel filter so about 2 months ago... Hopefully Saturday I can try the coffee can trick and take a look. Thanks!

beefmobile

sure thing. let us know how it works out

cruiser54

I would just replace the injectors on an old Renix for a coupla reasons. The upgraded 4 hole injectors give a better idle and throttle response. A big factor is that the originals are very prone to leaking at&vxp=mtr seam and spraying raw fuel on to your exhaust manifold causing a fire.

http://www.ebay.com/itm/Set-6-UPGRADE-1987-1995-Jeep-4-0L-Fuel-Injectors-/280801092750?fits=Make:Jeep&hash=item41610ca48e&it em=280801092750&pt=Motors_Car_Truck_Parts_Accessor ies

Seth2w

Thanks for the link. Are those what I need or 703s?

Zack92MJ

Yep
Edit: yep as in 703s

DFlintstone

Nice pasten there Cruiser! Here's "completed listings" for this date.

http://www.ebay.com/csc/i.html?_nkw=...=p3286.c0.m283

cruiser54

Yeah, what the heck happened?

Oh well.

If you get the injectors from Precision they are usually Ford Yellow top or Orange top. They're what you want. He knows his injectors. I've installed 3 sets of his injectors on Renix Jeeps with excellent results.

Seth2w

Ordered some today. I don't work weekends so I can start prepping and cleaning this weekend and just wait for them to come in. I'll post results...
BTW I had to show my wife this post to convince her to let me buy these things...shes gone on a saving spree these last couple of weeks..???

kjc

Of course we all want new (upgraded) injectors .. but you might want to check fuel pressure and other possible issues first. New injectors won't help if the fuel pump is going out. We don't want to give our better halves any more excuses for 'no more wasting money on that Jeep!'

beefmobile

ain't that the truth!!

every time i need something i get the "something ELSE is wrong with that big chunk of rust?! sheesh you might as well get rid of it because it's always something!"

Illuminator

From my experience to remove an injector on a renix 4.0L you have to pull the fuel rail, so all the injectors come out together but maybe it's possible and I just don't know it.

beefmobile

you may be right, i've never done it on a 4.0, it's just an old trick i know that thought i would share.

DFlintstone

X2, I need to add more bubble gum on my mismatched leaky, (inside) ,injectors, but I can still go OK. (I find rocking forward and back in the seat helps).

You wrote, "If I hit the gas hard its fine". I think it could be with Renix when you go past 80% throttle it goes into "open loop", and bypasses (some?) of the sensors. Does it pop back onto the manifold?
You can't get far checking sensors if you don't clean up the grounds first, defanently starting with that gang down below the dipstick.

^^Added--yea, that bracket on the TB is just a little in the way. GENTLY, they all come out, still clipped to the rail. Rock up and down, and a little side to side)^^