DaveAP Posted July 2, 2008 Share Posted July 2, 2008 Has always run great. Now runs rough. Starts and idles fine, just no get up and go. I think clogged catalytic convertor, or shot oxygen sensor. Any ideas? '87 brat. thanks, dave Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 2, 2008 Share Posted July 2, 2008 Has always run great. Now runs rough. Starts and idles fine, just no get up and go. I think clogged catalytic convertor Clogged cat's don't cause problems with power so much as they eliminate the scavenging ability and the mileage goes to poo. , or shot oxygen sensor. The O2's are narrow-band and thus have no effect on WOT operation. They are present for cruise mixture validation and correction only as they can only read 14.7:1 (stoich) mixture accurately or give a general indication of whether the ECU needs to go rich or lean to get to stoich. Any ideas? '87 brat. thanks, dave Valve adjustment (non hydro), tune up (cap, rotor, clean/gap plugs, wires if they look bad), check/adjust ignition timing, check ignition coil, clean air filter, inspect/clean PCV and EGR systems, etc. Make sure the secondary is opening on the carb, and look down the barrels - make sure the top cover gasket isn't melting into the carb as they do when they get old and eaten by fuel. GD Link to comment Share on other sites More sharing options...
one eye Posted July 2, 2008 Share Posted July 2, 2008 Clogged cat's don't cause problems with power so much as they eliminate the scavenging ability and the mileage goes to poo. The O2's are narrow-band and thus have no effect on WOT operation. They are present for cruise mixture validation and correction only as they can only read 14.7:1 (stoich) mixture accurately or give a general indication of whether the ECU needs to go rich or lean to get to stoich. Valve adjustment (non hydro), tune up (cap, rotor, clean/gap plugs, wires if they look bad), check/adjust ignition timing, check ignition coil, clean air filter, inspect/clean PCV and EGR systems, etc. Make sure the secondary is opening on the carb, and look down the barrels - make sure the top cover gasket isn't melting into the carb as they do when they get old and eaten by fuel. GD Just to add to this too, Also check both of the fuel filters, the one under the hood and the one right in front of the left rear tire right at the fuel pump. It could be worth a try to just replace these, 14 bucks and you could be good to go. Jeff Link to comment Share on other sites More sharing options...
DaveAP Posted July 2, 2008 Author Share Posted July 2, 2008 thanks for the replys.. I recently replaced the wires, air cleaner, fuel filter was a few months ago. I haven't done cap and rotor. Guess I'll go with the cheaper replacement stuff first. Link to comment Share on other sites More sharing options...
one eye Posted July 4, 2008 Share Posted July 4, 2008 thanks for the replys.. I recently replaced the wires, air cleaner, fuel filter was a few months ago. I haven't done cap and rotor. Guess I'll go with the cheaper replacement stuff first. Did you do both filters? Jeff Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 4, 2008 Share Posted July 4, 2008 Did you do both filters? Jeff +1 - it's always the nasty rear one that gets people. It's next to the pump under the car near the tank. People replace the vapor seperator thinking it's a filter (it is, but that's not it's primary job) without realizing that the real filter is before the pump and the seperator under the hood receives primarily clean fuel. GD Link to comment Share on other sites More sharing options...
one eye Posted July 4, 2008 Share Posted July 4, 2008 +1 - it's always the nasty rear one that gets people. It's next to the pump under the car near the tank. People replace the vapor seperator thinking it's a filter (it is, but that's not it's primary job) without realizing that the real filter is before the pump and the seperator under the hood receives primarily clean fuel. GD If you go to do this, get ready for gas to run down your arms. Audio_File (Chris) here on the board came up with the Idea of using golf Tees to plug the line once you remove the filters. you can get a bag of 100 of them at Wal-Mart for 1 buck. Jeff Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 4, 2008 Share Posted July 4, 2008 If you go to do this, get ready for gas to run down your arms. Audio_File (Chris) here on the board came up with the Idea of using golf Tees to plug the line once you remove the filters. you can get a bag of 100 of them at Wal-Mart for 1 buck. Jeff That's just silly. Clamp the lines off with a proper clamp - vice grips and two nickels, small c-clamps, welding clamps, etc, etc. There's no reason to get drenched in gas or try to stab a golfing T in the line (and how many mechanics golf anyway ). Last time I did one I didn't lose a drop on the ground or on myself (except my gloves of course). GD Link to comment Share on other sites More sharing options...
one eye Posted July 5, 2008 Share Posted July 5, 2008 That's just silly. Clamp the lines off with a proper clamp - vice grips and two nickels, small c-clamps, welding clamps, etc, etc. There's no reason to get drenched in gas or try to stab a golfing T in the line (and how many mechanics golf anyway ). Last time I did one I didn't lose a drop on the ground or on myself (except my gloves of course). GD That would work better, but if you don't have C-clamps and all that stuff, Its any port in the storm, you could use anything you want, But I just wanted to give him the Idea an assload of gas will come shooting out once you take the lines off. And if you are in the right place you will get it in the face. Jeff Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 5, 2008 Share Posted July 5, 2008 True - the lines will siphon the tank dry if you don't do something. Not everyone realizes that the first time. GD Link to comment Share on other sites More sharing options...
aba4430 Posted July 5, 2008 Share Posted July 5, 2008 I have done auto filters several times over, including on Subarus' , but just reading this I thought of our JD LX178 tractor faithfully doing service since 1995. It has a fuel cut off valve. Can something like this be installed in line prior to the main filter on our non-injected Subs? Can we get a valve that will allow adequate flow that the Subs need? This would make it very easy to replace filters? Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 5, 2008 Share Posted July 5, 2008 Can we get a valve that will allow adequate flow that the Subs need? This would make it very easy to replace filters? Not the modification I would pick first - just wouldn't use it often enough to justify. You would want to use a 1/4" ball-valve, and some 1/4" brass nipples. Easy enough to do - I just don't see the point when a pair of vice grips will do the same job. You are still going to get fuel out of the filter, etc - so you still need a drain pan and gloves. GD Link to comment Share on other sites More sharing options...
DaveAP Posted July 8, 2008 Author Share Posted July 8, 2008 Just did the cap and rotor. Made quite a bit of improvement. Still missing a bit,but much better. Now I'm fired up to follow through, will be checking the timing. Later, dp Link to comment Share on other sites More sharing options...
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