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danaspider
Samba Member
Joined: April 09, 2014
Posts: 8
Location: United States
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 Posted: Wed Apr 09, 2014 3:00 pm Post subject: loose power, occasional backfire |
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2 litre FI engine in 78 Bus. Has been running well, in fact we just drove it across the northern USA. Now, it starts easily, and seems to be running fine. After sometime, 5 to 10 minutes of driving, it will suddenly loose power. But not stall, continues to idle. In a few moments it will start pulling again.
Occasionally there is a back fire when power is lost. Even when has no pulling power it idles fine.
Ideas?
Dana |
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Paul Hoegemeyer
Samba Member
Joined: March 07, 2002
Posts: 40
Location: Lincoln Ne.
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| Posted: Thu Apr 10, 2014 8:19 am Post subject: |
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Had a similar problem with my 78 and it ended up being a plug wire going bad
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1978 passenger bus FI. camper special engine
1986 Brazilian DC
1979 Westy waiting on a TDI
1970 beetle |
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TomWesty
Samba Member
Joined: November 23, 2007
Posts: 3565
Location: Wyoming,USA
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| Posted: Thu Apr 10, 2014 6:31 pm Post subject: |
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Also, replace fuel filter.
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chicagovw
Samba Member
Joined: January 06, 2007
Posts: 1513
Location: Chicago IL/CHandler AZ
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| Posted: Thu Apr 10, 2014 6:36 pm Post subject: |
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| A few weeks ago this happened to my 78 FI. Someone here recommended that it might be a bad condenser-and that is what it turned out to be. |
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danaspider
Samba Member
Joined: April 09, 2014
Posts: 8
Location: United States
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| Posted: Wed Jun 11, 2014 5:39 pm Post subject: |
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2L 78 Bus, with FI. Was an intermittent issue of loosing power, but would still idle. Now has progressed to being there most of the time. I have changed plugs, wires, s tube intake, new fuel filter. Was better it seemed for a few days now worse than ever.
I have checked the fuel pressure and it is steady, did a compression check and find that #1 cylinder is 0. No funny noises.
I have not pulled the valve covers yet, but was wondering if this could be caused by a bad hydraulic lifter.
Any ideas? next step is to pull valve covers and look at springs and such.
Need guidance from the experts!!! |
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danaspider
Samba Member
Joined: April 09, 2014
Posts: 8
Location: United States
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| Posted: Wed Jun 11, 2014 5:47 pm Post subject: |
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Thanks for the feedback. I will do the check tomorrow and post the results.
It is interesting that it has been intermittent. That is why I was leaning toward a leaking hydraulic lifter.
Again, thanks |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 53210
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Jun 11, 2014 6:03 pm Post subject: |
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| danaspider wrote: |
| did a compression check and find that #1 cylinder is 0. No funny noises. |
Could be a number of things, the #1 cause is a loose valve seat followed by a burnt valve or damaged rings, it's not often a lifter hangs open constantly so chances of that are very remote but lifters sometimes wear off on the cam end or the lobe goes flat.
Bad news regardless of the cause, start by pulling off the valve cover and if nothing looks obvious remove the rocker assemblies and see if all 4 valve ends are level with each other (careful putting them back on, 9'lbs torque on the nuts max.).
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jdedini
Samba Member
Joined: January 15, 2009
Posts: 146
Location: Portland, Or
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| Posted: Wed Jun 11, 2014 6:28 pm Post subject: |
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After you get your valves sorted out, check your temperature sensor 2, distributor and coil while you are at it. All three have given me similar headaches.
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Justin
79' CA FI Tin Top Camper |
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geopanoramic
Samba Member
Joined: September 10, 2008
Posts: 195
Location: Moscow, ID
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| Posted: Thu Jun 12, 2014 6:42 am Post subject: |
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| Quote: |
Could be a number of things, the #1 cause is a loose valve seat followed by a burnt valve or damaged rings, it's not often a lifter hangs open constantly so chances of that are very remote but lifters sometimes wear off on the cam end or the lobe goes flat.
Bad news regardless of the cause, start by pulling off the valve cover and if nothing looks obvious remove the rocker assemblies and see if all 4 valve ends are level with each other (careful putting them back on, 9'lbs torque on the nuts max.). |
Some great advise. Finding zero in a cylinder is always a bit worrying. Dying coil can also a very frustrating experience and lesson in electrics serving the motor. Multiple things at the same time are a hoot.Good Luck! |
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danaspider
Samba Member
Joined: April 09, 2014
Posts: 8
Location: United States
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| Posted: Thu Nov 05, 2015 6:52 am Post subject: Re: loose power, occasional backfire |
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| danaspider wrote: |
2 litre FI engine in 78 Bus. Has been running well, in fact we just drove it across the northern USA. Now, it starts easily, and seems to be running fine. After sometime, 5 to 10 minutes of driving, it will suddenly loose power. But not stall, continues to idle. In a few moments it will start pulling again.
Occasionally there is a back fire when power is lost. Even when has no pulling power it idles fine.
Ideas?
Dana |
turned out to be a ba hydrolic lifter |
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