Hello everyone I'm new to the forum and joined in hopes of getting some help on an issue I'm having. First the truck is a Hijet S110P ENFS engine. The issue I'm having is on cold start ups it will not start. Sometimes it will start if I pump the gas pedal while cranking or holding the pedal completely down while cranking. Once it's started and warm it will fire right up and run great all day if I keep the engine warm. Once it sits overnight or until the choke closes it will not start again. Here's what I've done so far. Battery is new. Replaced fuel filter. Verified the fuel pump is pulling fuel from tank by method of pulling the fuel line to the carburetor and watching fuel shoot out while cranking. Verified good spark with grounded spark tester. Replaced the spark plugs just because. Symptoms pointed to bad carburetor (from researching on the forum) so I ordered a new carburetor from Don at Yokahoma motors. Arrived pretty quick and after I installed it, it's doing the same thing. Recheck and verified the vacuum hoses were in their correct locations via service manual book I purchased. Played around with the gas pedal and once I got it started adjusted the idle etc. it was running great. Let it cooled down and back to the same problem. No start when cold. I'm at a loss of what can be wrong. I even went the length of draining out the fuel tank and putting new premium fuel in there. Still same problem! Someone please help me before I go insane. Thanks
Interesting update. I forgot to mention I did a compression test before "warm" all 3 cylinders were at 130-135psi. Low? I did another compression test this time "cold" and all 3 cylinders were no more than 40psi. I then did a wet compression test squirting a few oz. of oil into each cylinder and compression jumped up to 80-90psi. So I'm pretty sure it's ring issue. For testing purposes I decide to squirt some oil into the combustion chamber and try starting it. Fired right up! It didn't want to idle but I held the pedal down until it warmed up and it was back to normal. Rechecked compression, and what do you know back up to 135psi. So how much of a difference can rings or even bad pistons differ from cold to hot? 95psi is a huge difference imho. Any inputs? Also anyone rebuild these engines have any suggestions?
It sure sounds like rings, with those numbers I would be looking at the air intake system because it sounds like it has been "dusted". Either a wrong filter or loose connection in the tubing between filter and carb. or someone ran it without a filter.
