Hello All, First post here and am looking for some help. Sorry in advance for the long post I want to make sure I get all the details for you all... I have a 1990 Hijet S83P that I picked up about 6 months ago. Ownership so far has been great. No issues. I did all the typical items I do when I get a new vehicle. Changed all the fluids (oil, transmission, diffs, brake, transfer case) , changed the filters, did the tune up kit from G&R (plugs and distributor, rotor, wires). New tires, all that good stuff. Everything was running great no issues on running, starting, performance etc. Everything was great. Then about 2 weeks ago after using it all day on and off I parked it for about 30 min when I was loading up some branches from a tree I took down. When I started it, it fired right up and then ran for about 45 seconds to 1 min and then died and I could not get it started. I let it sit for about 40 min while I walked my branches to the fire and then it started and ran fine. I parked it overnight then the next day went to start it , it started fine I went inside to let it warm up and about 2 min later I heard it die. I went outside and could not get it started. I took off the air filter tube to make sure it had good air supply, took out a plug to make sure it was getting spark , took off the fuel filter to make sure it was getting gas , took off the line from the fuel pump to make sure fuel was at the pump, sprayed carb cleaner / starting fluid (it sputtered from this and fired but would not continue to run), pumped the gas pedal a lot of times trying to prime it…etc etc etc. everything looked good but it would not start. I let it sit for about 30 min and then it started and ran just fine all the rest of the day. After this I checked vacuum lines that I could easily see and found a few that were not in great condition and were basically falling off. I replaced the ones in this condition one by one. There was one going to the fuel pump from the valve cover that was the worst, the others were all okay, but still were brittle and not tight so I replaced them. I also at this time replaced the plugs for a 2nd time just to make sure I did not get a bad batch. Then I tried running it, it ran just fine, and had no issues, so I figured I fixed the issue with the vacuum lines. Next day: I went for about a 50 min drive and parked it for about 30 min while visiting a family members house. Drove back another 50 min, parked for 5 min then went out again to the store. Drove 10 min to the store. Went in and then came out and started it to go home. Same thing as the night before, it ran for about 45 seconds and died on the road. I again pumped the gas pedal and got it running for a few moments but could not get it going long enough to move it so had to push it off the road. I kept pumping the gas and eventually got it running after about 15 min enough to get it home. I am not sure what to check next or where to go. This issue is one that is very bothersome because I don’t feel confident driving it on the road due to it dyeing randomly. Also, the other thing is I cannot always replicate it so bringing it in to a shop seems unlikely to help. If you have any questions please let me know. Im Sure I have missed some details but can fill you in. Thanks for any advice you might have, or recommendations on what to do next. I appreciate it greatly.
When you are having the starting issue, open the fuel cap. If it hisses out as it relieves pressure the charcoal canister is probably clogged. the needle valve on the carb is good for holding back a little over 2-psi. The fuel return line on the pump has a relief valve feeding it so fuel pressure stays constant, and the excess fuel, goes back to the tank. If the charcoal canister is clogged, the relief pressure goes up, and the pressure at the carb will overwhelm the needle valve and flood the engine. Solved it on mine bypassing the stock pump, with an electric fuel pump back at the tank and a regulator just before the carburetor.
Thank you for this information. I did notice that opening the tank does produce a hiss sound, sometimes worse than others which might explain why it is randomly dieing. I also noticed that after some time sitting without being run it does smell gassy at times. Do you know where the canister is, and is this something i can replace or clean or bypass instead of going to an electric pump?
It is right above the axle on the right side. I haven’t found a replacement. They can be rebuilt, using materials normally sold for use in aquarium filters, fiber glass and activated charcoal. You will need to cut your canister apart, and replace the fiberglass filter, and the activated charcoal. The are quite a few videos on YouTube showing how to do it. On my truck, I just bypassed the whole system. Then blocked the return line back at the tank, and installed an electric fuel pump with 3 to 5-psi outlet pressure, and then installed a regulator set for 2-psi, just before the carb. I left the stock fuel filter in place, and put one with replaceable elements just before the fuel pump. I was digging through some boxes last weekend and found a fuel pump, with a relief valve assembly for my old 77 Toyota pickup. I may install that in tank pump set up this spring when things warm up enough to work on things outside. I could get the truck in the garage to work on it, but I prefer to work on things with lots of gasoline smell outside. The stock fuel pump can then be removed, or you disconnect the fuel lines from it, but leave the vacuum line hooked up. The vacuum line pulls oil rich air from the valve cover into the fuel pump to keep it lubricated. Or, you can just remove the pump, and fabricate a block off plate. If you do that you can cap the vacuum line at the manifold. My dump bed made it really easy to get to the top of the fuel tank. On the normal truck it will be fairly easy to remove the bed if you have a helper, and do things from the top side. It will also be easier to access the charcoal canister with the bed off. and, it is really hard to get dirt and crud in your eye when you work from above.
Thank you for all the information. I will see if i can find some of those videos for rebuilding it. I will also have to see if i can find any canisters used or new, if I happen to find any ill let you know. Just to be clear when everything is working right, you shoud not hear any hiss when opening the gas tank right? Or is a small amount of pressure release normal? Thank you for the help I appreciate it.
Is working right you may hear a slight in going hiss. The vent from the fuel tank goes to the charcoal canister, and the canister is also connected to a vacuum port on the carb. Which applies a low vacuum to it to suck out any gasoline vapors and burn them. As opposed venting to atmosphere and polluting. When the canister is clogged the tank can’t vent and as the gasoline and air in the tank warm up, and get shaken up to get more fuel into the air, you will get an outward hiss as the pressure in the tank get relieved. It is the build up of pressure in the tank, which messes up the fuel pressure delivered by the pump to the carb. Becasue to send the fuel back to the tank through the return line, the little spring regulator in the fuel pump has to over come it’s spring, plus whatever pressure it is seeing from the tank presssure. So, if the tank has 2-psi of pressure built up, the relief valve doesn’t dump fuel and pressure back to the tank, until it gets to 4-psi on the outlet of the pump. And at about 2.5-psi, the fuel starts to go past the needle valve which controls the fuel level at the carb, flooding the engine out. It generally happens after you run for a bit and then shut down. So long as the engine is running, it can handle the over rich mixture and keep running. it will foul the plugs, but it will keep running. When you shut down, if there is more than 2-psi pressure at the tank, it will pressurize the whole system, and the fuel will go past the needle and into the carb, then out the overflow on the fuel bowl into the throat of the carb, and down into the intake manifold. When you try to restart the engine is flooded to the point it can’t fire off and get running. You sit for a while, and the fuel system looses pressure to the point it can’t push past the needle valve, and the gas in the intake manages to evaporate, or run down into your oil, and the truck can then start. You might try opening the fuel cap, to relieve the pressure, and then holding the throttle full to the floor next time you are having starting issues and see what happens. Pretty sure it will confirm what I have posted.
Thanks so much for this and the expliantion. That does all make sense to what is happening. I will be sure to try that the next time the no start action happens. I will confirm here . Seeing as its Jan and cant drive on the road my use will be less than normal this month, but i will give it a try arround the property and see what happens. Thanks again for the details and recomendations on where to go from here!
I found this unit on Amazon and with a little retrofit to mount it worked out perfect for me. ACDelco - Vapor Canister (SLP-1) (215-153) , Black https://www.amazon.com/dp/B000C9I9G...t_i_NZ4W04Q1QXK0R219P1G0?_encoding=UTF8&psc=1
it is also possible to re-build a charcoal canister and fill with new gauze filter.+ new activated carbon , here an example on a BMW charcoal cannister , click on page 3, Charcoal canister refurb http://www.km5tz.com/BMW 850i.htm
vacuum leaks are 85% of carb and idling problems, use a vacuum gauge or carb cleaner, carb cleaner will send the engine to high idle if you have a vacuum leak, make sure the vacuum port in the air cleaner canister is working properly, also check that your vacuum advance hose isn’t cracked coming off the distributor to the vacuum manifold tree. The vacuum manifold tree is brass on the bottom to go in to the block and plastic on top. Plastic wears out with time and will break or leak, which causes a vacuum leak. Some manifold vacuum trees are 3 or 4 port, make sure to replace it with a new one. When I buy parts I buy 3 at a time that way I have them on hand or in case they can’t get them any more. The vacuum manifold tree is located behind the carb. If you looking at the carb from the right side of the bed, it will be to your 1 O’clock tucked down inside. Remember to use a marker or different colored tape to mark the vacuum lines so you know where everything goes back too! Good luck!’
I wanted to thank everyone for the advice. I ended up solving the issue. after replacing some additional vacuum lines I performed a valve adjustment. It made it a bit better, but still was running rough. I then replaced the fuel pump and everything was resolved. So far running good. No onto the next issue. Thanks everyone. Eric
