• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

1981 Jeep Scrambler 4 Cylinder 2.5L 151 NOT STARTING!!

#1
So I have been lurking on this site for a long time and love all the friendly advice everyone gives on here, it is a really awesome community!!! Thought it was time I ask for some support myself.... I have had a cj5, cj7, wrangler, and now finally I got the one I have always wanted a Jeep Scrambler! Found it on Craigslist and somehow it was still available after 19 days online. I got it for a straight up trade for my 1997 Harley Sportster, which I estimate is worth maybe $3000?? SO I think I got hell of a deal. When I got there it definitely needed some TLC. The tank was out and the rear bed is rusted through really bad. All in all it wasn't terrible, just looked like it had been collecting snow, rain, and dust for awhile. I hauled it back to Michigan from Central Illinois and started going through it.... It washed up awesome. This thing is all original everything! Some rust holes in the floor and needed a fuel system overhaul, but man am I happy... I think I could sell it right now without it running for 10k (like I would ever sell it).

Anyways, to the issue at hand! I installed a new gas tank, new gas lines, new fuel pump, new starter, new battery, removed emissions and wallah one day it cranked and started after throwing gas down the carb and I let it idle and run for about 30 minutes. It ran really high RPM, but it was this winter so it was cold... so whatever, it eventually backfired a couple times and I turned it off...

Go to try it a couple weeks later and nothing... it just cranks and cranks and nothing. So I said screw it, I will start overhauling all of it ....

- Changed rotor, dist cap, ICM, Ignition Coil, spark plugs, plug wires, changed the oil, new fuel filter, new carb (rochester varajet II), capped off the vacuum lines, new valve cover gasket, new master cylinder... and I am still in the same situation. Still just cranks and cranks. IT WILL START if I pour gas in the carb and then it will just run out a few seconds later...

IT MUST have spark if it starts when gas is poured in the carb, right? Is this a fuel issue? Is the pump just wimpy and not putting enough fuel out? Is the fuel old and crappy now and doesn't start cause of that(has been sitting a few months)? I am scared it is not starting because of timing. That would not keep it from starting would it? That is probably something out of my skill level...

Any suggestions, let me know! This engine --- the 81 Iron Duke 151 2.5l is hard to get information or photos on.

Someone also said that it could be the ignition switch, but wouldn't it not start at all if it was the switch? Like I said it starts when gas is poured directly into the carb. When I hit the accelerator it sounds like there's gas squirting into the barrel. So I don't think it is the accellerator pump... I don't know. Sorry for all the information. Please help, thank you!
 

Otto

Boonie Basher
#2
Air in the line from the tank. Pull off line at carb see if gas is present. I used a 3psi electric pump to prime the line to the engine first time.
Stuck float. Carefully pour fuel in the screened hole in the center of the carb throat to fill bowl. This may float the float.
 
#3
Air in the line from the tank. Pull off line at carb see if gas is present. I used a 3psi electric pump to prime the line to the engine first time.
Stuck float. Carefully pour fuel in the screened hole in the center of the carb throat to fill bowl. This may float the float.

Awesome im going to hit this fuel system hard and make sure everything is flowing and working right! Unfortunately, it is a rainy as frick day in Michigan and my garage isn’t complete yet to do the work inside.... soon as this rain settles I’m all over the fuel lines, fuel pump, fill bowl, acc. Pump etc... thanks everyone for helping out!
 

jbeemer

CJ-8 Member
#4
Make sure to check the vacuum lines to the brake booster and the PCV valve. If one of those is broke, or the brake booster is bad, it'll suck too much air to idle or start............
 
Top