LiMBO - Late Model Bus Organization, International

Technical forums => Bay window concerns => Topic started by: vetterdog on July 27, 2009, 11:40:34 PM

Title: 79 Bus hard start / rough running after a short rest
Post by: vetterdog on July 27, 2009, 11:40:34 PM
I have heard this is common, but I haven't heard how to remedy it. My 79 Westy starts up and runs great, but after a short stop (say for a cold drink or grocery shopping) it doesn't want to idle. Also if it should stall after being re-started (after it's little rest) it's a real chore to get it fired up again. Turns over fine, but won't fire up.  As for the bus itself, it has a '74 type IV motor (1800) with the 79 heads and I just installed electronic ignition, which makes it run real nice, but the problem existed before the switch-over. Can anyone advise? All help/advice is, as always greatly appreciated.
Post by: MrLiMBO on July 30, 2009, 10:40:33 PM
Nothing comes to mind right off that might be causing your problem.  Though it sounds like a sensor. The sensor and the cylinder head might be the place to start.   My advice would be to get out your muli-meter, test light and Bentley book and start troubleshooting. The book has all the specs for each sensor and its fairly easy to troubleshoot that old Bosch system.
Post by: vetterdog on August 08, 2009, 12:15:42 AM
I feel kind of stupid admitting this, but my bus was about a quart and a half low on oil, so was running hot. It's always the simple things that are overlooked. My temp gauge isn't working. Gotta fix that.
Post by: St.Bus on August 09, 2009, 10:55:06 AM
Is it fuel injected?
if so sounds like a fuel problem.
temp sensor 2 is located near the #3 cylinder, may as well get a new one, if it is old, that can make the bus run rich if there is not the proper resistance.
First off get or borrow a vac gauge ($20) to look for vacuum leaks.
Verify that all vac hoses are sound, check all the lil clamps with a 1/2 turn of the screw driver to be sure they are tight.
Second , use a multi meter to test the cold start valve, again improper resistance will allow it to stay on like a choke even after the bus is hot, which sounds like the problem to me.
#3 replace the fuel filter, after a short drive , the pressure builds up and there may be small debris causing problems.
#4 does the idle go up when you pump the brake?if so there could be a major vac leak in the brake booster line.
when you first start the bus it'll run fine cus the cold start injector is adding fuel to help mix out the ratio of air from the brake booster leak, but when the cold start valve shuts off, there is  to much air..the possibilitys are endless,
look at richard atwells site. its like the Bentley online
Title: SO far....
Post by: vetterdog on October 19, 2009, 08:52:06 AM
Changed the #3 cylinder sensor no help, checked all vacuum lines, nothing. Cold start valve OK. Changed the fuel pressure regulator and it runs much better. Still sputters abit after a restart when it's warm, but I still have to change the fuel filter. Getting there by degrees. Snapped the clutch cable yesterday, but that's another story. Life is more of an adventure with an old VW don't you think?
Post by: vetterdog on November 04, 2009, 02:38:51 PM
Changed fuel filter but problem still persists. I stopped yesterday for 5 minutes, then it started, but it konked out on me and wouldn't restart. Frustrating as all get out. It will start when push-started though, so I've learned to shut it off on slopes.
Post by: St.Bus on November 17, 2009, 11:55:25 AM
remove and inspect the lil elbow that is attached to the aux air regulator, its worth a shot.
I replaced the elbow with another piece of tubing all together, when there is a crack in that the bus will idle fine, but give it gas and it dies, I think you have a major vac leak on a hose that when shifted opens a crack in it. if you get it to idle, go do the wiggle test while its running, careful though, you dont want to create any new leaks or cracks, ...................Joe
Post by: vetterdog on March 20, 2010, 05:52:55 PM
i have now replaced the ignition wires and the cold start valve, timed the thing, but it is getting worse. Now that the weather is warm, it is a pain to start, (turns over but takes a while to come to life) and when the engine gets warm, it doesn't want to idle. Seems like heat is a factor, but not the only one.  Next I will check the coil. I am thinking of offering a reward to anyone who can figure this out. Maybe at Westies in West Milford?
Post by: beebrew on March 21, 2010, 07:37:54 PM
Sounds like a possible vapor lock problem to me. If so, it's caused by parts in the fuel delivery system getting to to boiling point of gas. I am no familiar with this vintage to know if is a common problem. Is the motor overheating? Dipstick too hot to handle?
Post by: vetterdog on March 23, 2010, 10:46:40 AM
I though about that too, but it's not getting that hot. Unfortunately, my temp sensor (cyl head) guage isn't working. I am going to spend some time today on it, trying to assess weather my timing marks are in the right place, fixing temp guage, etc. I'll post any progress. Thanks,  Dave
Post by: vetterdog on March 24, 2010, 01:56:34 PM
OK, timing is fine, got the temp guage working too. No change in the issue at hand though. I stopped at the supermarket for a few things (express checkout no less!) and when I got back in the bus and started it, it wouldn't idle. It would die like it had a vacuum hose off. Stopped at a red light coming out of the supermarket parking lot and it stalled again. Started it and I drove for two monutes down the road, stopped at a light and it idled OK, maybe a little slow. By the next red light it idled fine.  So it's not teperature related, as it was a lot cooler when restarted than when I shut it off.  So far I've replaced points, ignition wires, fuel pressure regulator, cold start valve, fuel filter, fuel lines, spark plugs, cap and rotor, and clamped all vacuum lines.
Post by: beebrew on March 26, 2010, 01:32:21 PM
Please follow up on your results. You have my interest! If it were a vapor lock problem, I don't think letting it cool would make allot of difference. Once the gas boils, the vapors would have still displaced the fuel. Of course this assumes vapor lock is the problem. Did you replace the condenser along with the points? Just another piece.
Good luck.
Post by: beebrew on March 26, 2010, 01:38:11 PM
Oh, another thought. If this is carburetor engine, did you go through the choke? I have had one that did not close well when only marginally cool. It ran crappy until the engine warmed up more.
Post by: St.Bus on March 31, 2010, 03:41:28 PM
where do you live?
If you are near me Id be glad to help take a look with ya...
Im in western Mass. Have you tried putting an Ohm meter on temp sensor #1? ( white nub inside the afm ) also do you have the bentley?  Joe
Post by: vetterdog on April 15, 2010, 08:01:46 AM
I live in central West/Jersey, and the bus is fuel injected. it's actually got an 1800 motor from a Porsche 914 (I know, everyone has heard that one before, but I checked out the numbers) with the FI setup from the 2.0, (which needs a bottom end rebuild, whenever I get to THAT). I think we'll be at Granny Grose's and Westies in the Woods (Stokes State Forest), both in May. As I mentioned, I think I might offer a reweard to whoever can get this figured out. I also replaced the ignition coil and fixed the Cyl head temp sensor. It never reads above 350 at plug #3. It has been suggested that maybe it's a leaking injector, which would flood one cylinder while the bus sits. But it also exhibits this stalling behavior if I'm in stop-and-go traffic. Once I get to open road it's fine. All fuel lines are routed as original. I'm running out of things to check/replace! Another thing, went through state inspection and it failed for unburned fuel, they said it was pretty bad, but my spark plugs are a nice tan/gray color, just like they should be. Could there be an issue with the fuel delivery since the FI setup is from a 2.0 and the current motor isa 1.8???Thanks again to all for your intersest and advice.
Post by: St.Bus on April 30, 2010, 04:24:40 PM
hmm, do you know how to adjust the AFM?
look in the type2 archives to find some info on leaning out the mixture. I would put new injector 0-rings in there also if they are the original ones.

from the type2 archive
"And last but not least, the air flow meter provides the provision for idle mixture adjustment. There is a screw in the housing of the air flow meter that is used as a valve for an air bypass channel. The air flowing through this channel is not measured by the air flow meter and so affects the fuel/air mixture. Turning the screw clockwise blocks off the channel and so richens the mixture. Turning the screw counterclockwise opens the passage and so leans the mixture, as the extra air is not measured by the air flow meter and so the computer does not compensate for it. "
Post by: vetterdog on May 02, 2010, 11:40:10 PM
I have no idea how to adjust the AFM, other than adjusting the mixture screw. I will look into it and post any results.  Today, I ran the bus for a bit, then let it sit and pulled the spark plugs to see if any were wet to indicate a leaking injector. They were all nice and dry, which is good, since I replaced all the injectors a few years ago, (so they're not the originals). I poked aroung the engine and realized that the thermostat cable wasn't adjusted properly, so the flaps connected to the cable were staying closed. I though that this might be the whole trouble, so I adjusted the cable and took the bus for a test drive. It ran really well and I noticed it was running about 50-75 degrees cooler too.  I had set the timing a tiny bit advanced to smooth out the idle, )which through this whole ordeal has been set higher and higher just to keep the darned thing idling) but after a few minutes of driving I noticed that it was idling very fast, so I stopped and turned the idle screw way down, back to about where it was originally set and it ran nice and smooth and quiet. I was sure I had it solved. I got back home and decided the timing should be reset, so I went about doing so. Now the bus was sitting after use, and as soon as I wanted to start the engine to use a strobe it reverted back to it's nasty habit of not wanting to idle. It would die instantly as soon as I took my foot off of the gas pedal. So I set the timing statically but still it wouldn't idle. It's like the problem was solved temporarily, but as soon as the bus sat still for 10 minuted or so I was back to square one.  I wasn't about to back out the idle screw 3 or 4 whole turns just to get this thing to stay running. I need to figure this out, as I have a few campouts I have promised the kids I would take them to. (Granny Grose's and Westies in the Woods, Stoke State Forest NJ) I'm getting so frustrated and desperate that I might resort to taking the thing to an actual mechanic, which for me would be the ultimate defeat.
Post by: vetterdog on May 04, 2010, 08:28:17 PM
The plot thickens. After realising that the air flaps have been closed, I figured I'd better check my valve clearances, since they're probably out of whack. Well, they were all tight, so I reset them, but now the bus won't start at all. Now I'm backing up to having to figure out why it won't start, which will mean compression check, etc. etc. and I've made some plans for camping in a week and a half. Panic isn't far off, I think.
Title: what a long strange trip it's been
Post by: vetterdog on May 05, 2010, 08:57:42 AM
Thanks to all who've been following this oddessy and helped along the way. Realised that my dizzy clamp had migrated southwards and wasn't letting the shaft seat all the way down into its hole, so fixed that, checked the compression (all good, right around 100) and got the bus started. It smoked a bit, heavily at first, but tweaked the idle and test drove it this morning and it runs pretty good. Smoke has stopped altogether.  As of right now it's looking good. I won't declare victory just yet, I will drive around a bit tonight and tomorrow and see how it goes. I'll be holding my breath for the next day or so.
Post by: St.Bus on May 05, 2010, 04:17:48 PM
hey it sounds like the same issues I had, I recently just redid the top FI  portion, all the hoses and boots and injector 0-rings, and when I started it up, the idle was way high!!! so I had to cut it back like 4 whole turns, also when I rechecked the timing it was at 12BTDC, which was 7.5 with the vac I static timed it back... I think you have some vacume leaks in there..prolly in the intakes or injector seals..Joe
Post by: vetterdog on May 11, 2010, 08:38:43 AM
Thanks for the tips, I am off from work today will look into those spots and let you know. Seems to be running a bit hot too. Getting there by degrees. (pun?)
Post by: vetterdog on May 12, 2010, 11:37:22 PM
So far so good, but now I notice it's struggling a bit in the lower rpms when accelerating. I can feel it hesitating, at the beginning of each gear and if I cruise at the bottom of each gear's range (like 40mph in 4th gear) it bucks a little, sometimes a lot. I suspect valves need re-adjusting after all the travails of this long process, but I'm not ruling out something else. (Burned valve, or electrical) Will post any developments. Meanwhile, we will be schlepping out to Granny Grose's Friday regardless, so anyone else heading out there, be on the lookout for us on the shoulder of Rts 78 or Old 22. Look for smoke/cursing/wrench throwing.
Title: Finally
Post by: vetterdog on September 19, 2010, 11:55:07 PM
Turns out the intake air tube was not tightened and all I needed to do was tighten it and problem was solved. Got a lot of maintenance done in the process though.
Title: 79 Bus
Post by: prez on September 21, 2010, 08:28:34 PM
Vacume is the key to the Air Flow Control systems, ['75-'82.]   Look for larger leaks, like these, as they were made to bediagnosed  with basic tools.   I find them to be quite relialable.
Title: Re: Finally
Post by: St.Bus on October 07, 2010, 05:09:12 PM
Quote from: "vetterdog"
Turns out the intake air tube was not tightened and all I needed to do was tighten it and problem was solved. Got a lot of maintenance done in the process though.

Isnt it usually the case..go to the ends of the earth and its something minor eh?
good part is, all those other items may have failed if you increased the vacuum by thightening the boot. now, you know they are out of the way and dont need replacing for sometime now...Joe