Engine hiccup?

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Jivermo
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Engine hiccup?

Post by Jivermo » Wed May 31, 2017 3:20 am

I was driving my '78 FI Westy the other day down US 1, and it gave a little burp, like it cut off for a moment. It has been running quite well. I got to my destination, but when I was leaving, it was hard starting, in that it would start, and then crap out. After a few times, the engine fired up and I drove the 9 miles home without incident. When I start it cold, it cranks right up. I checked the fuel pump, and it works well, it appears, pumping out a good stream with the AFM jog test. Any clue as to what I ought to look at?

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sgkent
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Re: Engine hiccup?

Post by sgkent » Wed May 31, 2017 2:56 pm

have a smoke generator? Maybe a small vacuum leak

Have points - check for a broken rubbing block

The two issues may or may not go together so be lenient treating them as one. For example - the engine may have ingested a small one time shot of water causing it to hiccup - it happened to me once in my CJ7 and one in my 1971 bus. The CJ7 died for about 4 or 5 seconds and the bus for 2 or 3. Or a small piece of carbon may have held a valve open (CJ7 did that a couple times in its life), or shorted out a plug (dad's F84 Olds did that once causing a cylinder to drop out for a few minutes intermittently). My Opel GT back in the day did that on a fairly new set of NGK plugs. Turned out to be a bad shipment of plugs. Putting the old ones back in resolved the issue - which started on a trip from LA to SF and by the time we got to Dublin we were running quite poorly. I didn't think we would make it up the Altamont Pass. Headed home it started doing it again so I put the old plugs in on a whim which were still in a box in the back area - and all the issue went away.

All that said - the hard starting when cold points to either the TS2 being loose, or that wire being loose, or a vacuum leak. Last - the California buses had a special fuel elbow called a Bird's Beak. The end breaks off and floats around the tank just waiting to plug the inlet line. When it settles near that spot it can intermittently cause weird things to happen like no or low intermittent fuel availability. If you have a small video camera you can look inside the tank for a metal ring and a small black piece of rubber. Do it with enough fuel in the tank to displace the air to fuel mixture.
Thank You -

Merlin The Wrench

Jivermo
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Re: Engine hiccup?

Post by Jivermo » Wed May 31, 2017 3:17 pm

Thanks. Cold, it starts up fine. It's when it's hot-it starts, runs a second and dies, as though not getting gas. Couple of times of that, and then I can get it going. These symptoms began rather suddenly. I'm going to go through it tomorrow, starting at the points. It's not a California bus, and the tank is clean. When I took the fuel lines test screw out and put a hose on it, I got a nice, consistent stream. It sure acted fuel related, though. Appreciate the input. I'll report back.

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Amskeptic
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Re: Engine hiccup?

Post by Amskeptic » Fri Jun 02, 2017 5:23 am

Jivermo wrote:
Wed May 31, 2017 3:17 pm
Thanks. Cold, it starts up fine. It's when it's hot-it starts, runs a second and dies, as though not getting gas. Couple of times of that, and then I can get it going. These symptoms began rather suddenly. I'm going to go through it tomorrow, starting at the points. It's not a California bus, and the tank is clean. When I took the fuel lines test screw out and put a hose on it, I got a nice, consistent stream. It sure acted fuel related, though. Appreciate the input. I'll report back.


Classic symptom of a loss of residual fuel pressure.
Get a fuel pressure gauge on the "tee" and check the fuel pressure drop on hot engine just after shut off. See Bentley for specification, but I think it is 1 bar (14 psi) for 15 minutes.
Colin
(either the fuel pump check valve or the fuel pressure regulator check valve)
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 206,865 miles
Naranja - 77 Westy . . . 132,040 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 94,225 miles

Jivermo
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Re: Engine hiccup?

Post by Jivermo » Fri Jun 02, 2017 6:48 am

Thanks! Will do, if this rain ever lets up.

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asiab3
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Re: Engine hiccup?

Post by asiab3 » Fri Jun 02, 2017 9:47 am

Jivermo wrote:
Fri Jun 02, 2017 6:48 am
Thanks! Will do, if this rain ever lets up.
Isn't that the whole point of the 73+ Westies? We can work on it from the dry comfort of laying on our bellies while the rain pours down. :pirate:

IF you have a residual pressure leak, this nice article on here lists the technique for narrowing down the cause:

http://www.itinerant-air-cooled.com/viewtopic.php?t=213

Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Re: Engine hiccup?

Post by Jivermo » Fri Jun 02, 2017 10:03 am

Great writeup! Thanks for the link.

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BellePlaine
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Re: Engine hiccup?

Post by BellePlaine » Tue Jul 21, 2020 7:14 pm

Howdy all,

I'm experiencing an issue with my 75 FI 1800 bus similar to Jivermo's original post. I get random hiccups at various rpms, however I haven't yet experienced this symptom at idle.

It also happens sometimes, that the bus will turn over but not start after having run. This seems to happen after a quick stop, like getting gas. Then, on every second try, the bus fires right up as usual. It's happened three times over the past Fall and this Summer.

The random non-start and random hiccups began at the same time last summer and both are still occurring. Before these issues occurred, I replaced the fuel line as it had been at least 10 years. I also replaced the my old Frankenstein'd AFM with a Bus Depot replacement.

For hundreds of mile the engine ran very well. Then I experienced a hiccup at acceloration and a non-start later that day at the gas station. One more non-start the following morning, and then no issues for a while.

I have a fuel pressure gauge. The pressure on a warm engine at idle is 30 psi (regulator hose on) and 40 psi (hose off). After 15 minutes with the engine off the pressure is 34! psi (hose on) and 28 psi (hose on) 30 minutes after shut down. Am I within spec? The Bosch FI Manual Test Chart says 2.2 - 2.6 bar, or 32 - 37.7 psi so maybe not?

Any advice is appreciated as I try to chase down this gremlin.

Hope everyone is well out there.
1975 Riviera we call "Spider-Man"

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Mulcheese
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Re: Engine hiccup?

Post by Mulcheese » Sat Jul 17, 2021 7:11 am

I see that this post is now 1 year old but just checking for any updates. I ask because I have experienced the random hiccups at highway cruising for some time. On a very rare occasion I have had a slight hard start warm. I have always pointed to fuel but not sure where. Time for more research.
"attending to things in the moment with curiosity and acceptance."
____________________
82 Vanagon Westy - aka: Honey Badger - "cause she just dont give a ...."

cegammel
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Re: Engine hiccup?

Post by cegammel » Sun Aug 15, 2021 3:00 pm

These all sound very much like what I was experiencing before my complete breakdown yesterday. Time for more sleuthing.

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Amskeptic
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Re: Engine hiccup?

Post by Amskeptic » Wed Sep 22, 2021 8:41 am

I, too, have had some random hiccoughs over the past now-100,000 miles put on NaranjaWesty.
First time was a failing condensor that got a little water incursion where the green wire goes into the condensor body.
Second time was I forgot to tighten the s-boot clamp on the AFM.
Third time was just a lousy too-rich mixture as I climbed in elevation.
Fourth time was 27,000 miles of breaker point pitting.
Colin
(the possibilities are endless, and half the battle is to do good work where you can check off *what it isn't*)
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 206,865 miles
Naranja - 77 Westy . . . 132,040 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 94,225 miles

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