Missing under power

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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billyg
Posts: 16
Joined: 15 years ago
Location: Athens Al

Missing under power

#1

Post by billyg »

Searched the forum over and while I found some descriptions that were close, nothing matched exactly, so here goes: '83 720 SD22 http://nissandiesel.dyndns.org/viewtopi ... highlight= Sat for 8 years without runnning, I've replaced everything rubber associated with the fuel system under the hood, diaphragm, adjusted timing (drip method), filters, boiled the tank, did not replace the check valve on the tank nor the associated hoses from metal lines. see here http://nissandiesel.dyndns.org/viewtopi ... highlight= The truck ran fine for the first couple thousand miles then one night this past winter (it was COLD that night) i was driving and it missed, just one little flutter (~60 mph), then picked back up and ran fine the rest of the way. Then about 3 weeks later, I got in it early one morning to go to work and when I went to third gear, it acted like a gas engine that had water in the fuel so I turned around and came back home (went to work in another car). I"ve checked vacuum lines (no leaks), the IP timing is where I set it at with the drip method (no movement) and I even looked at the section on this forum about fuels lines and replaced some factory clamps with the balkamp ones mentioned......to no avail.

It starts missing the most when under acceleration, although it will sit there and idle all day and never miss a lick, and depending on how bad the missing is (worse sometimes than others) the valves sound 'knockish'. All this make me think fuel but I'm sorta at the point where I need Al or Phil or somebody to jar my thinking...............I'm at a loss.

Bill
"Let me control a nations currency and I care not who makes the laws" N.M Rothschild
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asavage
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#2

Post by asavage »

If the symptom is especially bad when it's cold out, read down to "Tale of Woe" in this thread.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.
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philip
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Location: Southern California, USA

Re: Missing under power

#3

Post by philip »

billyg wrote:-snip-
It starts missing the most when under acceleration, although it will sit there and idle all day and never miss a lick, and depending on how bad the missing is (worse sometimes than others) the valves sound 'knockish'. All this make me think fuel but I'm sorta at the point where I need Al or Phil or somebody to jar my thinking...............I'm at a loss.

Bill
Engine knock under any load suggests the obvious. A nozzle

But a not so obvious can be an air lock found one line between the injection pump and the nozzles.

Try this: While the engine is idled, crack open each line where it fits to each nozzle. The engine RPM will drop until you close it again. IF the engine starts knocking (sometimes the knocking will become LOUD), just open / close / open / close that line meeting the nozzle for 5 second periods. Once the knocking ceases, move to the next one.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"
billyg
Posts: 16
Joined: 15 years ago
Location: Athens Al

Al comes thru again....

#4

Post by billyg »

After much angst and replacement of fuel hoses/clamps, bleeding the injectors while running, replacing the secondary filter, cutting off the muffler, i finally ordered one of the CORRECT primary fuel filter (as noted by Al in the above post), which has a SCREEN in it- NOT- a paper element and my problem is solved. Now all I've got to do is get the muffler, or some kind of muffler, put back on and I'm back to normal. at least as normal as I can be. Thanks again Al...................

PS, I kinda like the straight pipe as I can hear EVERY grunt the engine makes, but the wife says no :)
"Let me control a nations currency and I care not who makes the laws" N.M Rothschild
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