renob123 Posted June 3, 2009 Share Posted June 3, 2009 This is for my '85 Brat GL. It used to go at least 70mph, now it's 45mph if I'm lucky. There's a weird hesitation when I give it a little gas. The hesitation starts at about 1k rpm and goes until about 2k rpm. However, it idles at 1k rpm and sounds fine. When I'm on the gas at, say, 2500 rpm or more, it pulses. I changed both fuel filters yesterday. Any ideas what it is? Here's a list of things I'd like to check, but don't know how to: -Vacuum advance -Timing (does this make sense if it idles normally?) -Misc hoses (which ones should I look at?) -PCV (do I even have one? Where is it?) Thanks. Jacob Link to comment Share on other sites More sharing options...
ihscout54 Posted June 3, 2009 Share Posted June 3, 2009 First thing Ide check is if the choke is opeining when warm. Then you will need to search for vac leaks. The PCV is at the manifold end of the driver side large hose to the air cleaner. It has a tee at the top, more like an F one hose to the cleaner and one to the valve cover. You can check the vac advance, but I doubt it would cause that much trouble. Link to comment Share on other sites More sharing options...
renob123 Posted June 3, 2009 Author Share Posted June 3, 2009 First thing Ide check is if the choke is opeining when warm. Then you will need to search for vac leaks. The PCV is at the manifold end of the driver side large hose to the air cleaner. It has a tee at the top, more like an F one hose to the cleaner and one to the valve cover. You can check the vac advance, but I doubt it would cause that much trouble. I forgot to mention that the choke is fully open when warm:) Should I replace the PCV then? Is there anything else? Jacob Link to comment Share on other sites More sharing options...
ihscout54 Posted June 3, 2009 Share Posted June 3, 2009 Be sure youre getting good fuel pressure. It could be a plugged up main jet or dirty carb internals. You might try to see if the bowl vent is working. While you are checking for vac leaks, spay a lil carb cleaner around the base of the carb to rule out the gaskets, and throttle shaft wear. (while idling) Aslo, check your ignition system. Disty cap rotor wires + plugs. Is there any other symptoms that might lead us in the right direction, like smoke from exhaust, foamy coolant etc? Link to comment Share on other sites More sharing options...
renob123 Posted June 3, 2009 Author Share Posted June 3, 2009 Be sure youre getting good fuel pressure. It could be a plugged up main jet or dirty carb internals. You might try to see if the bowl vent is working. While you are checking for vac leaks, spay a lil carb cleaner around the base of the carb to rule out the gaskets, and throttle shaft wear. (while idling) Aslo, check your ignition system. Disty cap rotor wires + plugs.Is there any other symptoms that might lead us in the right direction, like smoke from exhaust, foamy coolant etc? The coolant is fine, and there's no unusual smoke coming from the exhaust. I'll add the bowl vent to the list of things I check once I get home. The ignition stuff I think is fine because it idles ok. The only thing would be the coil or the distributor's advance that would cause this, I think. I'll swap out coils tonight. I'm not sure how to check the vac advance, but you said the problem is too big to be that. I may just check it anyway for kicks:) It started happening after a friend took it through a mud pit at the last rallyx. For the first 1/8th mile or so, the car runs fine. After that is where the problems start. Pushing on the gas nearly kills it, the tach hits about 0 rpm, then the car moves forward slowly. Does that help? Jacob Link to comment Share on other sites More sharing options...
kilgore Posted June 3, 2009 Share Posted June 3, 2009 Sounds quite similar to the performance of my EA82 when the headgasket was blown... no low end compression. Just throwin' it out there. Link to comment Share on other sites More sharing options...
renob123 Posted June 3, 2009 Author Share Posted June 3, 2009 Sounds quite similar to the performance of my EA82 when the headgasket was blown... no low end compression.Just throwin' it out there. There would be oil or something in the coolant if that were the case, right? It might be something to check more thoroughly. Jacob Link to comment Share on other sites More sharing options...
ihscout54 Posted June 3, 2009 Share Posted June 3, 2009 Im sure you checked your oil, and you already said the coolant was fine. Dont get too worried yet, but I have seen a couple HG leaks/head issues that just cause the antifreeze to foam up, not even really over heat till the antifreeze is completely suds. They were AMC 232/258 inline 6's though. So yea there doesnt have to be a significant mixing of fluids. But for that matter you could have any number of compression related problems that you just dont notice at idle. If you are concerned do a compression test. But stick with the simple stuff first, unless you see steam from your tail pipe or excessive foam in the antifreeze after a short run or a lot of bubbling while running I wouldnt go that direction yet. Link to comment Share on other sites More sharing options...
renob123 Posted June 3, 2009 Author Share Posted June 3, 2009 Im sure you checked your oil, and you already said the coolant was fine. Dont get too worried yet, but I have seen a couple HG leaks/head issues that just cause the antifreeze to foam up, not even really over heat till the antifreeze is completely suds. They were AMC 232/258 inline 6's though. So yea there doesnt have to be a significant mixing of fluids. But for that matter you could have any number of compression related problems that you just dont notice at idle. If you are concerned do a compression test. But stick with the simple stuff first, unless you see steam from your tail pipe or excessive foam in the antifreeze after a short run or a lot of bubbling while running I wouldnt go that direction yet. Ok, for "simple stuff", I plan to: -Dump some Seafoam in the gas tank to clean any jams or anything -Check the carb -Replace the PCV valve -Replace the vac advance line -Put on the right fuel filter Does that sound about right? Jacob Link to comment Share on other sites More sharing options...
ihscout54 Posted June 3, 2009 Share Posted June 3, 2009 Its a good start. The pcv is probably needed, and its not too hard to check. Thouroughly inspect all vac. lines. Most of the issues Ive had were all leak related. Until you rule out vaccume system leaks its hard for our heads to go anywhere else. There are alot of possibilties, even a plugged up cat/exhaust. How wicked was that mud bog anyways? Link to comment Share on other sites More sharing options...
renob123 Posted June 3, 2009 Author Share Posted June 3, 2009 Its a good start. The pcv is probably needed, and its not too hard to check. Thouroughly inspect all vac. lines. Most of the issues Ive had were all leak related. Until you rule out vaccume system leaks its hard for our heads to go anywhere else. There are alot of possibilties, even a plugged up cat/exhaust.How wicked was that mud bog anyways? It was pretty wicked, considering the cars attempting to navigate it. Plus, I could have probably been up to 45 or 50 mph in my fast car in other spots:grin: I'll post some pics when I find them. Is there a smart way of checking vacuum lines? Jacob Link to comment Share on other sites More sharing options...
markjw Posted June 4, 2009 Share Posted June 4, 2009 (edited) Get a new can of carb cleaner. Make sure it comes with the little red straw so you can direct the spray into specific spots. Start your car and let it idle. Spray the carb cleaner a little at a time at places like the intake manifold gaskets,base of the carb,vac line connections. If you have a vac leak in a particular area. A vacuum leak will suck in the carb cleaner and your engine rpm will increase at least a little. Sometimes alot. Just listen for it. Take your time and be carful of the acc. belt/belts. I found a really Big vac leak in the intake manifold gasket of a sedan I picked up recently. It had the same symptoms your describing about your vehicle. Don't spray this stuff into your carb while your engine is running. In fact,I'm pretty sure its only for cleaning the outside of your carb. Edited June 4, 2009 by markjw Link to comment Share on other sites More sharing options...
renob123 Posted June 5, 2009 Author Share Posted June 5, 2009 Update: I brought it into the shop yesterday. I got it back last night. I can only seem to duplicate the problem on the road when the engine's under load, like accelerating or going up a hill. After that, I'm able to kill the Brat just by putting my foot on the gas pedal the right amount, even in the driveway. Does this help with diagnosis? I'm replacing the cap and rotor, plugs and coil in order to rule out ignition. The shop adjusted the timing. Any feedback? I'll start looking for a replacement carb that I can run while I learn how to inspect this one, if the above changes don't fix it. Thanks. Jacob Link to comment Share on other sites More sharing options...
Yo'J Posted June 5, 2009 Share Posted June 5, 2009 Are you getting air? Clogged filter or intake? Link to comment Share on other sites More sharing options...
renob123 Posted June 5, 2009 Author Share Posted June 5, 2009 Are you getting air? Clogged filter or intake? I took the intake off and was able to replicate the problem, so I doubt it's that. The filter is pretty new and in good shape (considering this is my rallyx-only car). Thanks though. Jacob Link to comment Share on other sites More sharing options...
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