BRDM Driver Posted April 1, 2016 Share Posted April 1, 2016 Just took the Scorp out for a test run after the clutch rebuild. There was a hesitation in the engine with misfire at around 1000 to 1500 rpm where it loses power and almost stops. As this coincides with the clutch engagement, it made pulling away rather tricky. Once you get through 1500 rpm, it ran fine. Idle was fine too. Very similar to what it was always like when running from cold, but now when hot. This got progressively worse such that I had to keep the engine above 2000 rpm all the time to get back home! Luckily it was only around the corner and I made it back without having to stop anywhere... Once I got home, the engine stopped as soon as I lifted off the gas to let it idle and wouldn't restart. So any ideas where to start looking? I'm going to check fuel filter and plugs first, then distributor, then carbs. (I have a load of spare carbs and ignition parts to swap out with). Cheers, Quote Link to comment Share on other sites More sharing options...
GeePig Posted April 1, 2016 Share Posted April 1, 2016 So many places to start... If it is a misfire rather than a hesitation, I would start with the ignition system, myself. How long has it been since it last ran? trevor Quote Link to comment Share on other sites More sharing options...
Diana and Jackie Posted April 1, 2016 Share Posted April 1, 2016 Try remove the fuse on the speed limiter, if a Belgian engine it will have a fuse holder adjacent to the coil, if British the fuse holder is incorporated into one of the spare cable outlets on the coil housing. Diana Just took the Scorp out for a test run after the clutch rebuild. There was a hesitation in the engine with misfire at around 1000 to 1500 rpm where it loses power and almost stops. As this coincides with the clutch engagement, it made pulling away rather tricky. Once you get through 1500 rpm, it ran fine. Idle was fine too. Very similar to what it was always like when running from cold, but now when hot. This got progressively worse such that I had to keep the engine above 2000 rpm all the time to get back home! Luckily it was only around the corner and I made it back without having to stop anywhere... Once I got home, the engine stopped as soon as I lifted off the gas to let it idle and wouldn't restart. So any ideas where to start looking? I'm going to check fuel filter and plugs first, then distributor, then carbs. (I have a load of spare carbs and ignition parts to swap out with). Cheers, Quote Link to comment Share on other sites More sharing options...
BRDM Driver Posted April 1, 2016 Author Share Posted April 1, 2016 Thanks for the suggestions! I've just been starting my diagnosis... The plugs look a little hot having a slight whiteness on the electrode. I just took out the fuel filter and it was full of water with a tide mark of rust about half way up! The fuel pump is missing it's filter altogether! I'm thinking it's running lean and the carb jets are getting clogged with all the rusty crap in the fuel filter. It's been standing for about 6 months and it fired up fine yesterday. The problem developed after about 30 mins actual driving and then got worse and worse. Just out of interest, is there a trick to priming the fuel system? I see there is an air bleed on the filter but the manual says it's not used... Cheers! Quote Link to comment Share on other sites More sharing options...
Diana and Jackie Posted April 1, 2016 Share Posted April 1, 2016 There are 4 filters, one filter fitted between the pump and petrol tank, one in the rear of the petrol pump both you've identified and 2 around the jets in the carb. The pump filter is a common item on eBay. Sounds like everything needs stripping and cleaning. There should be no need to prime anything, listen to the tick of the pump, once it slows the carburetor is full. It may take a while to slow if you drain the system as it has to refill and self prime. On the rear inside of the pump is a magnet, which will probably need cleaning too. You were dead lucky to get home. The rubbish in the system will have accumulated in years. If after cleaning the fuel system it still shows symptoms then pull the limiter fuse. Diana Thanks for the suggestions! I've just been starting my diagnosis... The plugs look a little hot having a slight whiteness on the electrode. I just took out the fuel filter and it was full of water with a tide mark of rust about half way up! The fuel pump is missing it's filter altogether! I'm thinking it's running lean and the carb jets are getting clogged with all the rusty crap in the fuel filter. It's been standing for about 6 months and it fired up fine yesterday. The problem developed after about 30 mins actual driving and then got worse and worse. Just out of interest, is there a trick to priming the fuel system? I see there is an air bleed on the filter but the manual says it's not used... Cheers! Quote Link to comment Share on other sites More sharing options...
BRDM Driver Posted April 1, 2016 Author Share Posted April 1, 2016 There are 4 filters, one filter fitted between the pump and petrol tank, one in the rear of the petrol pump both you've identified and 2 around the jets in the carb. The pump filter is a common item on eBay. Sounds like everything needs stripping and cleaning. There should be no need to prime anything, listen to the tick of the pump, once it slows the carburetor is full. It may take a while to slow if you drain the system as it has to refill and self prime. On the rear inside of the pump is a magnet, which will probably need cleaning too. You were dead lucky to get home. The rubbish in the system will have accumulated in years. If after cleaning the fuel system it still shows symptoms then pull the limiter fuse. Diana I've cleaned up the fuel pump, but it's not pulling any fuel up. It's running doing a fast tick but the fuel filter bowl is still dry. Obviously an air leak there somewhere as it's not pulling any vacuum. Normally it ticks fast for a few seconds and then goes to the slow tick. The bayonet cap on the bottom of the pump doesn't look like a really good way of getting an air tight seal! I've put more fuel in, before you ask! Quote Link to comment Share on other sites More sharing options...
Diana and Jackie Posted April 1, 2016 Share Posted April 1, 2016 There should be a rubber ring on the inside of the cap if there isn't you should be in a noah's ark of petrol? Sounds like the fuel outlet of the tank/rubber bag maybe blocked and or an air leak? Diana I've cleaned up the fuel pump, but it's not pulling any fuel up. It's running doing a fast tick but the fuel filter bowl is still dry. Obviously an air leak there somewhere as it's not pulling any vacuum. Normally it ticks fast for a few seconds and then goes to the slow tick. The bayonet cap on the bottom of the pump doesn't look like a really good way of getting an air tight seal! I've put more fuel in, before you ask! Quote Link to comment Share on other sites More sharing options...
sirhc Posted April 1, 2016 Share Posted April 1, 2016 Get it running properly from a new or clean Jerry can using an adaptor for a generator to start with. Worry about the mess in the tank later, that's a big job. I've had fuel pumps which ticked but didn't pump before. Do you have a spare? Quote Link to comment Share on other sites More sharing options...
BRDM Driver Posted April 1, 2016 Author Share Posted April 1, 2016 I'm thinking that the problem is a blocked carb, probably due to all the muck in the fuel filter... I took the pipe off the fuel pump outlet and it pumps great, so tomorrow I'll blow the main fuel line through and check all the carb jets. I did manage to get it running again tonight, but only with the cold start out and the engine got hot pretty quick, so I think it's running really lean... Thanks for all the help so far! Quote Link to comment Share on other sites More sharing options...
BRDM Driver Posted April 2, 2016 Author Share Posted April 2, 2016 Had a look in the carb, it had fish swimming about in the float bowl... well it could have done, there was a lot of water in there... This had caused a bit of corrosion which made a residue almost like sawdust, this was in the slow running jet. So I have just cleaned out the whole carb and all the jets and it's running fine now. It still has a slight stutter if you blip the throttle until it gets past 1500 rpm. If you ease the throttle it runs fine, but it doesn't like a sudden blip, so i guess that's the accelerator pumps putting a bit too much fuel in at that speed. It's always been like though and it usually improves once its fully warmed up. just need to put the firewall back, seat and top armour.... In how many vehicles do you have to take the drivers seat out to get at the carb...:rolleyes: Quote Link to comment Share on other sites More sharing options...
sexton Posted April 5, 2016 Share Posted April 5, 2016 I believe the CVRT carb is very similar to a Ferret carb. In that case, it sounds like the accelerator pumps (there are two of them) are putting out too little fuel, not too much. These heavy vehicles with relatively small engines require a HUGE pump shot to prevent bogging on acceleration. Looking down the carb bores, if you floor the gas pedal with the engine off, you should see a steady, solid, continuous stream of fuel from the two pump nozzles. If you don't, check if the pump inlet strainers are plugged. This is common on Ferret carbs as the pumps take fuel from the very bottom of the bowl, so sediment tends to collect there, which plugs the mesh strainers. Malcolm Quote Link to comment Share on other sites More sharing options...
BRDM Driver Posted April 7, 2016 Author Share Posted April 7, 2016 I believe the CVRT carb is very similar to a Ferret carb. In that case, it sounds like the accelerator pumps (there are two of them) are putting out too little fuel, not too much. These heavy vehicles with relatively small engines require a HUGE pump shot to prevent bogging on acceleration. Looking down the carb bores, if you floor the gas pedal with the engine off, you should see a steady, solid, continuous stream of fuel from the two pump nozzles. If you don't, check if the pump inlet strainers are plugged. This is common on Ferret carbs as the pumps take fuel from the very bottom of the bowl, so sediment tends to collect there, which plugs the mesh strainers. Malcolm Hi Malcolm, I cleaned the accelerator pump filter gauzes when I checked all the other jets and the diaphragms look ok too. Good stream of fuel going down the venturi when you hit the accelerator. I'm not sure if the hesitation is due to the clutch biting or it's just a flat spot in the engine fueling. It certainly gets better as the engine warms up. Quote Link to comment Share on other sites More sharing options...
sexton Posted April 8, 2016 Share Posted April 8, 2016 BRDM, a couple more suggestions. Did you check the jet was clear in the economizer valve (if you have one) and that the spring was opening it on low manifold vacuum? That richens the mixture under load. And try screwing the two idle mixture screws out a bit more to richen idle. I had a Ferret that bogged a bit on each gear shift and that fixed it. Malcolm Quote Link to comment Share on other sites More sharing options...
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