datzenmike Posted January 22 Report Share Posted January 22 Which will give you the fuel pressure only. Nothing about what's going on in the carburetor or even if it is the carburetor. Quote Link to comment
Dusten Posted January 22 Author Report Share Posted January 22 No, but it gives me an idea on which half of the fuel system to look at. And takes really no effort. I can T in the line running from the pump to the carb. It's honestly less effort than shutting off the truck really fast to try and catch the fuel bowl being low. This was fine. The truck sat through an extreme cold snap and now it's having an issue. I'll look at wearable parts first. Quote Link to comment
Dusten Posted January 22 Author Report Share Posted January 22 (edited) I don't exactly have the ability to pull the truck over. We don't have parking or sidewalks were I live. Just ditches. I'm 20 minutes from town out here. Edited January 22 by Dusten Quote Link to comment
datzenmike Posted January 22 Report Share Posted January 22 Well anywhere safe.... maybe at 4 AM? I'm expecting the fuel pressure to be within the stock 3-3.9 PSI To burn the mixture has to be somewhere near 14.7 to 1. To burn in the exhaust pipe there has to be fuel and air roughly in those proportions, so where does unburned fuel and air come from? Well a cylinder that does not fire would dump half a liter of it into the hot exhaust manifold. Intermittent miss fire could be a spark jumping to ground because it's much harder to at the spark plug under load. Maybe just a dirty plug. Maybe a lose wire in the primary side of the coil. Did you try pulling each plug wire separately and driving it to see if it stops? Quote Link to comment
Dusten Posted January 22 Author Report Share Posted January 22 (edited) 49 minutes ago, datzenmike said: Well anywhere safe.... maybe at 4 AM? I'm expecting the fuel pressure to be within the stock 3-3.9 PSI To burn the mixture has to be somewhere near 14.7 to 1. To burn in the exhaust pipe there has to be fuel and air roughly in those proportions, so where does unburned fuel and air come from? Well a cylinder that does not fire would dump half a liter of it into the hot exhaust manifold. Intermittent miss fire could be a spark jumping to ground because it's much harder to at the spark plug under load. Maybe just a dirty plug. Maybe a lose wire in the primary side of the coil. Did you try pulling each plug wire separately and driving it to see if it stops? No I haven't touched it because my daughter had a volleyball tournament all day. It's probably going to sit till next weekend. My only window to work on the truck is from about 8 am to noon because i work 10pm-7am and my shop has my daughter's truck frame and cab occupying the entire shop while I cut out the floors and cab mounts. I'm going to run it and pull plugs and see which look lean. Edited January 22 by Dusten Quote Link to comment
Dusten Posted January 27 Author Report Share Posted January 27 Checked valves for fun. 2 exhaust valves were a little tight. One intake was a little tight. Adjusted all that were off Pulled the plugs. They look even. popped the air cleaner and everything is wet Truck sat with the hood open. Cleaned it up. Sprayed down the carb with cleaner. Ran the truck and cold the vacuum was fine for a tired motor I can't find my adapter for my fp gauge to t into these fuel lines so I haven't checked yet. I ran it to the gas station filled it with fresh fuel and tossed some heet in to see if I have a water issue. Unlikely but ya never know. I'm going to take it for a long drive shortly and grab a fuel filter. 2 Quote Link to comment
Dusten Posted January 27 Author Report Share Posted January 27 New filter - no change Pulled the lid and verified float level and check the jets to see if they're plugged. Everything was good. Swapped out fuel pumps. No change. It feels like it's draining the bowl. The more load on the truck or the longer i stay in it the more it acts up. It revs in neutral cleanly to 5k or so. I won't rev it higher. Freeway speeds you can feel a slight hiccup and any throttle input creates an issue. Pulling a hill creates issues. Driving around town is fine, lean into and it goes but will eventually act up if you stay in it. Quote Link to comment
datzenmike Posted January 27 Report Share Posted January 27 Well the following will also apply to the Weber... On 1/21/2024 at 3:57 PM, datzenmike said: You have the stock Hitachi Carburetor? It has a sight glass on the front of the fuel bowl. If the float is properly set the fuel level will be in the center. Check and see. If it is, take for a drive and floor it till it acts up. The point here is to see what the level in the float chamber is while it's acting up. So to preserve the fuel level in the carburetor get the clutch in and the ignition off ASAP so the engine stops immediately. Then slow and pull over. Check the fuel level in the sight glass. Just remember if the engine is allowed to run for any time it will refill the carburetor so get it stopped fast! This will lay to rest that the carburetor is running out of gas. If the float chamber is empty then there IS a fuel delivery problem. If half full of gas then it's something else. Quote Link to comment
Dusten Posted January 27 Author Report Share Posted January 27 How do you see in the goat chamber on a Weber? It's under the lid. I'm not terring the carb apart in the middle of nowhere Quote Link to comment
datzenmike Posted January 27 Report Share Posted January 27 I re suggested this because you said you said "Pulled the lid and verified float level and check the jets to see if they're plugged. " so what does it matter where you do this? Take precautions with you. Quote Link to comment
Dusten Posted January 27 Author Report Share Posted January 27 (edited) 52 minutes ago, datzenmike said: I re suggested this because you said you said "Pulled the lid and verified float level and check the jets to see if they're plugged. " so what does it matter where you do this? Take precautions with you. I pulled the lid and verified I had the float set correct in my shop. I am not tearing the carb apart along side the road. Disconnecting the choke linkage with that little c clip is a pain in the ass and I'm not going deal with this away from home. I'll hook up my fp gauge and watch it under load. If pressure dips, volume is also dropping. I just need to get the correct T. Edited January 27 by Dusten Quote Link to comment
datzenmike Posted January 27 Report Share Posted January 27 You changed the pump and filter so it's unlikely two pumps do the same thing. Possibly there is a restriction in the fuel line to the tank. Take the outlet from the pump and direct into a suitable container, pull the coil wire off and turn the engine with the starter. Pump should spurt fuel out in strong streams if working. If weak stream maybe a restriction on the inlet side. The fuel pressure may be normal but there is a small blockage at the carburetor float needle. Quote Link to comment
Dusten Posted January 27 Author Report Share Posted January 27 Or... I can simply hook up my fp gauge and use actual tools to troubleshoot I can watch it under load when the condition occurs. If it's dropping at higher rpms then there is likely a restriction. If it isn't the carbs coming off. 2 Quote Link to comment
Dusten Posted February 1 Author Report Share Posted February 1 Alright I finally got some more time to screw with it I tore the carb down and cleaned all jets, and the needle and seat for the float. I made sure any and all passages were free of any residue or junk. New gaskets at the base and lid. Threw it back on and it made no difference. I decided to finally hook up fuel pressure Its a little high at idle, but nothing concerning. I took it for a drive. Fuel pressure was mostly stable. It dips once, right as the engine pops, but I think it was a product of the engine popping and not the other way around. Excuse the video i quick rigged the gauge At this point I was getting frustrated. I blew out the hard line to the fuel system with compressed air. The more I drove the truck the more it felt like ignition. I tried like mike asked at pulled a plug. But the truck ran so well at light throttle that pulling a plug induced more issues than anything else so i gave up. I checked timing. It was solid at 11* and was advancing with throttle. I pulled the plugs because i got to thinking that with the truck overheating maybe a gap opened or a plug cracked. I reset all gaps to .040 and the problem cleaned up, but still wasn't gone. So i picked up a new set up plugs and gapped them to .040 and threw them in. I drove it to work today, about 34 miles. 13 miles of that is freeway, which was a real issue when i was fighting the truck. It drove great. Held 65 with no issues. Pulls to 5k with ease. 3 Quote Link to comment
banzai510(hainz) Posted February 1 Report Share Posted February 1 I would try a different distributor if it really troubles you. if still persisits My 521 was daily driven for ever and the ditributor bushing would be worn and cause issues but normal driving was fine Quote Link to comment
datzenmike Posted February 1 Report Share Posted February 1 Sounds like a back fire through the carburetor.... Try reducing the plug gap to say 0.038" Quote Link to comment
Dusten Posted February 1 Author Report Share Posted February 1 14 minutes ago, datzenmike said: Sounds like a back fire through the carburetor.... Try reducing the plug gap to say 0.038" It's not doing it anymore with the new plugs Quote Link to comment
datzenmike Posted February 1 Report Share Posted February 1 NGK right? Maybe the others were counterfeit? Well that's good news. I was thinking a damaged intake valve. 1 Quote Link to comment
Dusten Posted February 1 Author Report Share Posted February 1 Yes ngk. I'm curious The plug was damaged when the engine got hot when I ran it out of coolant going to inspect the plug when I get home from work tonight Quote Link to comment
datzenmike Posted February 1 Report Share Posted February 1 Detonation or pinging can damage a plug, cracked porcelain or even tearing the ground strap off. And detonation can easily happen in over heating conditions. Quote Link to comment
Stoffregen Motorsports Posted February 1 Report Share Posted February 1 The engine got hot when you ran it out of coolant? That's never a good thing. 1 Quote Link to comment
datzenmike Posted February 1 Report Share Posted February 1 Never do that. Valve seats are an interference fit and are chilled in the freezer while the head is heated to 300-400F to expand the opening so it fits. Getting it that hot because out of coolant seriously risks dropping a valve seat. Then there is also the chance of warping the head and blowing the head gasket. Stop and put ditch water in it if you have to. 1 Quote Link to comment
Dusten Posted February 2 Author Report Share Posted February 2 (edited) Jesus Christ you guys act like I drove a 100 miles I posted on here about it I left for work. About a mile in I noticed my temp gauge was high. I turned around and drove home and checked coolant. It was non existent. The radiator has sprung a leak. Filled it. Started it. It wouldn't build heat. T-stat was damaged in the process. Replaced water pump, hoses, t-stat, radiator, fan clutch. This issue arose after all that. The gauge didn't peg. It didn't ping while running hot. It was just higher than normal. Edited February 2 by Dusten 1 1 Quote Link to comment
datzenmike Posted February 2 Report Share Posted February 2 Well it's THAT IMPORTANT. Aluminum heads are really bad for overheating damage is all. Quote Link to comment
Dusten Posted February 2 Author Report Share Posted February 2 I'm aware. Checked the 4 plugs 5.5 Kohms 5.7 Kohms 5.4 Kohms 1.9 Mohms Found the problem 2 Quote Link to comment
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