Kwiknez Posted October 3, 2016 Share Posted October 3, 2016 (edited) Hello, new to the site and hope y'all can help me. I just purchased a dual range 86 Subaru GL for a price I couldn't turn down. Engine idles like a dream, but once rpm's start rising it starts to stumble upon itself causing it to not go over 30 mph. New fuel pump, fuel filter, previous owner said he rebuilt carb. Any tips or ideas on what might be causing problems? Timing? Read something about needle valve in carb clogged possible cause. Any help would be great thanks. Mike 1986 Subaru GL 1999 Subaru Impreza 2002 Subaru Outback Edited October 3, 2016 by Kwiknez Quote Link to comment Share on other sites More sharing options...
subnz Posted October 3, 2016 Share Posted October 3, 2016 (edited) It could be the needle jet / float valve not set correctly or the main fuel jet partially blocked (water / dirt) The previous owner may not have done a good job of rebuilding carb.. What condition is the air filter in? If problem still persists, Also look at ignition, spark plugs, leads, coil, distributor - centrifugal advance (weights- shaft ) / vacuum advance unit etc leaking vacuum hoses - usually breakerless distributors don't need to be timed but worth checking (10 degrees btdc) at idle rpm with a strobe timing light connected in series to no.1 lead and pointing it at timing marks though timing cover inspection hole at top of bell housing onto flywheel timing marks (underneath spare wheel) Edited October 3, 2016 by subnz 1 Quote Link to comment Share on other sites More sharing options...
87subbomber Posted October 3, 2016 Share Posted October 3, 2016 I had this same problem after carb rebuild. Checked timing, it was good. All new vaccum lines,new ignition system, plugs and wires and fuel pump were all new. One part i didnt check until limping it home was the choke. Sure enough it was stuck closed. This was flooding the engine and would not allow me to get over 3.5k rpms. 1 Quote Link to comment Share on other sites More sharing options...
Kwiknez Posted October 15, 2016 Author Share Posted October 15, 2016 Well got car running decent today. Replaced idle mixture screw and idle rpm screw. Bought a timing light and set about timing. Went to loosen bolts for distributor and they were already loose, hmm. Check timing and it was about 15 or so degrees btdc I think. The marks were really rusty and hard to see. Brought it down to about 8 or so and car started behaving a little better. Actually idling about 800-900 rpm. Took for a test drive and much more responsive, but still when I put pedal down, I hear secondaries opening but very slow to accelerate. I think I can get car up to about 50 mph now yay. Still need figure this out before I set it on fire. 1 Quote Link to comment Share on other sites More sharing options...
subnz Posted October 16, 2016 Share Posted October 16, 2016 (edited) Timing could be retarded now as forgot to mention that need to remove vacuum hose off vacuum advance unit and set rpm at 800 while setting timing with strobe timing light. 8 degrees btdc is correct as per service manual. Its a good idea to clean / highlight / mark timing marks on fly wheel with "twink / white out / correction fluid marker to make them easier to see when timing with strobe timing light. Reconnect vacuum advance / vacuum hose - with engine running, timing should advance slightly about 2 degrees (check with timing light) and rev engine with strobe timing light still pointing at timing marks. Timing should advance up to 20 - 30 BTDC and return to about 10BTDC at idle this shows that centrifugal advance / weights are working correctly in distributor. Driving test ie full throttle in 3rd gear from 2000rpm - sluggish acceleration, backfiring - timing retarded - lots of detonation / pinging - timing too advanced - reasonable performance with slight initial denotation - timing about right. Take aircleaner off (engine off) and look down primary choke and work throttle to see if accelerator pump in carb is spraying fuel in there. Run engine rev from idle and do the same but care just in case back fire through carb ie flaming etc to see if engine picking up smoothly without hesitation / splutters etc ie a nice smooth hiss / roar when secondary choke opens Edited October 16, 2016 by subnz 1 Quote Link to comment Share on other sites More sharing options...
Kwiknez Posted October 16, 2016 Author Share Posted October 16, 2016 (edited) When you remove the hose off vacuum advance should I plug it or just leave it open? When I checked timing today I just removed the hose and didn't plug it. I did clean up the timing area to allow better sight. I will check tomorrow what happens when I plug hose back on while timing. 3rd gear acceleration at 2000 rpm results are just pure sluggish. I rebuilt the carb with new accelerator pump and gaskets. I however didn't replace floats but they did look good and measured right. I also checked to see if gas pumped in when throttle worked. And there was a healthy stream spraying in. I recorded a video of me driving today to show what is going on. youtu.be/_6qs9undipA Edited October 16, 2016 by Kwiknez Quote Link to comment Share on other sites More sharing options...
subnz Posted October 16, 2016 Share Posted October 16, 2016 (edited) Yeah should have said also to plug vacuum line as this will affect idle speed - may need to re adjust idle screw for 800rpm to retime. Watched / listened to your video - car sounds sluggish like ignition timing could be still retarded or / and fuel issues with carb still and also stopping /surging at 3000 / 3500 rpm could mean secondary choke not opening or running lean (mixture) as well - float setting perhaps - not enough fuel in float bowl. Are there any vacuum / air leaks like vacuum hoses , inlet manifold gaskets perhaps / gasket mounting between carb and inlet manifold, air leak in vacuum hose and brake servo ? etc PCV valve clogged open ? These hitachi carbs are a pain in the arse - had issues with mine when I rebuilt it can't of done a very good job as it wouldn't idle. So went and got a 2nd hand one from wreckers - didn't touch it inside and bolted it straight on and was not perfect but much better than my previous attempt . It ran ok after that for a few years. Here's a link that I googled if it helps on carb http://mastertechmag.com/pdf/1987/12dec/198712IS_Hitachi2Barrel.pdf and vacuum leaks http://www.aa1car.com/library/vacleak.htm Also it could be ignition as well ie coil / spark plug leads breaking down under load. especially main lead between coil and distributor cap . rotor / distributor cap - clean contacts of white corrosion inside. Unfortunately it's a case of trial and error going through stuff systematically to eliminate possibilities. Edited October 16, 2016 by subnz 1 Quote Link to comment Share on other sites More sharing options...
subnz Posted October 17, 2016 Share Posted October 17, 2016 (edited) Also it wouldn't be a silly idea if you could get your hands on a compression tester and check compressions to get an idea of engine condition. 150 - 160 psi for engine in good condition (service manual) Need to warm up engine 1st then remove all spark plugs then get someone to crank engine while you hold compression tester in each spark plug hole in turn when crank engine - need to hold throttle wide open as well while cranking / compression testing. With spark plugs out the colour of the porcelain insulators will be a guide to whats happening as well https://www.ngksparkplugs.com/about-ngk/faqs/spark-plug-faqs/how-do-i-read-a-spark-plug Edited October 17, 2016 by subnz 1 Quote Link to comment Share on other sites More sharing options...
Kwiknez Posted October 18, 2016 Author Share Posted October 18, 2016 I think I might have figured out the problem. Well maybe. I had air cleaner assembly off, checking vacuum again and when it was idling I revved engine to make sure fuel was going in, at below 3000 rpm fuel was squirting in primary no problem but no fuel at all in secondary. Checked vacuum diaphragm and there was no vacuum going to it, I manually moved the secondary and it revved no problems. So problem seems to be no vacuum to secondary diaphragm, now how to fix that I don't know. 1 Quote Link to comment Share on other sites More sharing options...
Kwiknez Posted October 18, 2016 Author Share Posted October 18, 2016 I brought car to a place that is highly recommended by some local Subaru fans. Told them what I have observed and they said they will check it out. Hopefully they can tell me what needs to be done or fix cheap. 1 Quote Link to comment Share on other sites More sharing options...
Kwiknez Posted October 18, 2016 Author Share Posted October 18, 2016 (edited) Also it wouldn't be a silly idea if you could get your hands on a compression tester and check compressions to get an idea of engine condition. 150 - 160 psi for engine in good condition (service manual) Need to warm up engine 1st then remove all spark plugs then get someone to crank engine while you hold compression tester in each spark plug hole in turn when crank engine - need to hold throttle wide open as well while cranking / compression testing. With spark plugs out the colour of the porcelain insulators will be a guide to whats happening as well https://www.ngksparkplugs.com/about-ngk/faqs/spark-plug-faqs/how-do-i-read-a-spark-plug I plan on replacing the belts anyway. Eventually going to replace everything to keep silver going for long time. Yeah I am going to rent a compression tester from local auto parts place this week sometime. Edited October 18, 2016 by Kwiknez 1 Quote Link to comment Share on other sites More sharing options...
DaveT Posted October 18, 2016 Share Posted October 18, 2016 I am not sure at what rpm and load the secondary should begin to open and deliver fuel, but at low rpm and load, it should not be doing either. Quote Link to comment Share on other sites More sharing options...
Kwiknez Posted October 18, 2016 Author Share Posted October 18, 2016 Well the gas starts spraying about 3000 rpm or so to allow the transfer to secondary I believe. So problem is not having any vacuum from port in carb that secondary attaches to. Quote Link to comment Share on other sites More sharing options...
robm Posted October 18, 2016 Share Posted October 18, 2016 Is the diaphragm that opens the secondary in good shape? If it has a hole, it won't open. The port may be OK. 1 Quote Link to comment Share on other sites More sharing options...
Kwiknez Posted October 19, 2016 Author Share Posted October 19, 2016 I put finger on port from carb and revved and felt no vacuum at all. Got car back from local shop today, wanted someone to look at it. Apparently both head gaskets are blown and the cat is clogged. So have to figure out what to do now. Would love ej swap but that's spendy. Guess I will do mechanical conversion of the hitachi and replace cat. Then change head gaskets eventually, and timing belt at same time. Quote Link to comment Share on other sites More sharing options...
DaveT Posted October 19, 2016 Share Posted October 19, 2016 You can test for the blocked cat by carefully loosening the nuts that hold the y pipe to the engine. Get about a 1/2" gap in there, and run it. It will be loud. If it runs normally, the exhaust is blocked. If it runs pretty much the same, the problem is something else. Or maybe a combo, but don't put a new cat on until you know the rest is right. 1 Quote Link to comment Share on other sites More sharing options...
Kwiknez Posted October 20, 2016 Author Share Posted October 20, 2016 (edited) Fixed the secondary problem by going mechanical. youtu.be/pRtPH4A6JF4 Edited October 20, 2016 by Kwiknez Quote Link to comment Share on other sites More sharing options...
Kwiknez Posted November 1, 2016 Author Share Posted November 1, 2016 Fixed. All along the cat was plugged and pretty broke inside. Replaced with new Y pipe and cat and voila instant power. 2 Quote Link to comment Share on other sites More sharing options...
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