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PostPosted: Mon May 19, 2014 8:49 am 
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Location: Corrales, New Mexcio
Ok wizards of the diesel world, here's my most recent reality. First, let me bring you up to date:

The 3.4 rear end went in (replacing the stock 3.7 ratio) with flying colors. Drove the vehicle with no noise coming from that area...a winner!

Went to a local repair facility when I realized trying to install a new walker muffler and tail pipe section was beyond my active skills. Had the owner of the shop use one of his new mufflers due to the obvious cheapness of the walker unit I had bought at O-Reilly's when compared to what he showed me. He also owns a local Meinicke muffler shop in Alb. Should know his mufflers, one would think.

My Chinese new tires seemed great...but at 53mph on the odometer I get a vibration in the steering which goes away as speed continues to rise...only to 60mph on the odometer (which I suggest is more like 63-65 due to the fact I did not replace the trans gear for the new ratio rear end). Had the tire shop re-balance all 4 but problem still remains.

Might have a set of crappy tires, will go through my suspension system myself to see if anything is causing this (ideas anyone?) before asking the tire company to replace the tires...prior to I will take the right front, move to the right rear while bringing up the right rear to the front and doing likewise on the left and then demand a workable solution if the problem still remains.

Got the new shocks in the rear, here come the fronts, will look at the suspension bushings, etc. Had it four wheel aligned (Hunter machine with computer print out provided) prior to new tires installed by same shop (to which I was directed by a friend...still a friend but warned I am not happy!).

Now, on to the lack of upper speed. Ok, the manufacturer shows a speedo good for 85mph...beyond making the sale, this vehicle should have a top speed on a flat road of what? Got to be more than 63mph, even adjusted, I would think.

So...my mechanical pal gives me a call later Sunday and suggests this possibility: Could the new muffler be the wrong type for my diesel and in fact be "restricting" the exhaust flow, thus reducing power, thus limiting top end?

Damn thought makes sense...

How would/could I tell? That is my question for those who take the time to read this new posting, along with the front end wonders.

I should also add that this vehicle is a blast to own thus far and drive around the city! I am watching my gas mileage to see if it goes down which might support the idea that the muffler is wrong for this type of engine.

Thanks for any advice and suggestions. I like this mini truck a lot so far, only I want it to go faster in the top end...so I can take it out of town...up to North Dakota, on the highways...at a speed I want and within it's potential, in order to pass those oil rigs making the farmers rich!

What is this vehicle's potential? Side question: If this engine can't produce a 70 to 75 mph top end, is there a "drop in" engine of same make that will do this and still provide good/great gas mileage? That is my last but least back up plan/thought at this point in time. I've looked at the add-on of turbos...not sure of that trick for me.


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PostPosted: Mon May 19, 2014 8:33 pm 
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First, your speedometer is now under-reading by 9%. So your indicated 60 is actually 65--your high estimate.

Second, tire size will also affect the accuracy and I don't know if your tire size is stock (195/75 X 14, if I recall correctly).

Sorry, I don't recall your year and transmission type. But when my '83 was brand new, it would bury the 85 mph speedometer (probably about 90 mph) with the 3.73 rear end. After 30 years, you may not get quite that much out of it, but if running well it should still hit 85 (assuming 5-speed 2wd). Whether the 3.42 rear end slows it down or speeds it up is not certain, all we know is that it lowers your RPM at top speed.

I had severe performance problems with mine, and finally (after years of poor performance) pinned it down to a bad Cold Start Device (CSD). It was not allowing the timing to advance properly. At its worst, it would barely go 60.

Jack

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PostPosted: Tue May 20, 2014 4:17 am 
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Location: Corrales, New Mexcio
Great, just great...however, I am working on a program to discover what's what via potential area testing.

Phase one will be to remove my "new" muffler and replace it with just a muffler pipe. Then we'll see what little restriction will do for power.

And yet...that cold start problem that you know who was kind enough to provide some insight will most definitely be added to our growing list of areas to examine and explore.

Good news is that I have both factory manuals on this model and year. This is an 81 long bed with original 5 speed trans, now with the 3.4 rear end, speedo shows 112k miles and previous owner (not living) claimed it was a dog at the upper end. It has original size tires with 80 rims on all four.

When I took off what appeared to be the original muffler I did comment on how "heavy" it was, especially when compared to the Walker unit and even the present unit the repair shop choose to install.

Running up through the gears till about 50mph seems to be fine, with going around town at 35 to 45 (I know the speedo is lower than actual due to not replacing the trans speedo gear). It is pushing the truck past 50 that seems to take so long and it won't go that much higher than 63mph on the speedo.

Bet me, I'm gonna smarten up on this cold start system too!

When engine is cold, I turn the key, wait till the yellow light goes out, then rotate the key to start it. Starts right up, runs rough, warms up, idles like a kitten, smooth and smiling! No smoke of either black or white. Fuel mileage was about 35mpg on first tank (after sitting outside in sun since '97...I drained the old fuel, etc. prior to starting), I expect 2nd tank to be less due to that run up to Santa Fe with the wind, etc. when I realized it would not go over 62mph on the speedo unless downhill and saw the speed radically drop trying to go uphill, so much so that I had to change gears.

Again, thanks for the serious input. Every idea has merit in this hunt as far as I am concerned. Will keep you posted.


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PostPosted: Tue May 20, 2014 5:15 pm 
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I think you missed my point. The CSD (Cold Start Device) can make your injection timing completely unpredictable, without causing poor starts. That's what mine did. It always started beautifully, but had performance problems. Someone had suggested I remove the device and I was skeptical. When I finally did, it was like an overhaul. And besides the suddenly revived performance, the truck went from 29 mpg in town to 36 mpg (and even once 38 mpg) instantly.

Jack

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PostPosted: Thu May 22, 2014 11:28 am 
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This gets funnier and funnier as I come back to the site and read Joe Isuzu's latest, informative and sincere response!

Two days ago I began to think about the previous owner's claim that his vehicle was slow going. My mechanic friend said one way to begin elimination was to remove the new muffler, install a temp straight pipe and see what happens.

I thought, knowing that the original muffler was on the vehicle when I received it, that the owner might have spoken the truth as best he knew it, and that with 111k miles on the speedo, being a Sandia Labs brainiac, he most certainly had replaced the "timing belt" and this is where I might wish to take a look.

I had bought a new timing belt with gasket kit a few weeks ago...it was on my list, along with that oil line behind the amp unit (note to others: I don't have that new part, the oil line, does a member sell these?). Noticed the upper rad hose was tired and the clamp was not tight, leaking at this area. Tightened the clamp, stopped the leak, but it seems to come back...time for new hose and possible clamp too, hoping the radiator doesn't have a tube problem.

Thought, Hey...I've got a radiator problem, it needs to come out for the timing belt...why not kill two birds with one shot?

So, my game plan is to take out the radiator, look for a crack on the upper outlet on the radiator, then when the timing covers are removed, verify the timing marks, etc., then call in my mechanic friend to aid in replacing this belt (being the genius mechanic I am...never did a timing belt replacement...I need skilled backup for sure!) and then make super sure when the new belt is installed that the timing marks, etc. are all "on the money" prior to closure.

I had a hunch this may be where a problem could be...incorrect setting of the timing marks, even if off by a tooth, etc.

Now, here comes Joe Isuzu and clarifies his previous "cold start system" comment as to how it effects the timing of the vehicle if inoperative or malfunctioning wherein it produces poor performance...my main concern relative to top end speed, or lack of speed over 62 mph.

Which leads me to think...ok, I get the timing belt on correctly, all marks, etc. lined up as factory specs demand, and that the previous view prior to removing the old timing belt showed all marks lined up correctly...bingo!

Timing belt not my problem area...but what about that cold starting system that Joe Isuzu warned?

That then becomes the next issue to check out and verify. Off to my factory manual for education, then re-read Joe's advice, and check this baby out.

Ladies and Gentlemen...place your bets!

Something tells me that Joe Isuzu may be on to something here and if in fact this whole enterprise comes to verify that his suggestion is in fact my problem area (or one of the problems) I may then wish I had a daughter to give him in marriage for solving my power issue at top end!

I'm going to re-read his previous post on this to see if he also included info as to how to verify CSS is working correctly or if he is reading this long winded post he might add the methods he uses to check out this system.

Either way, it is off on this adventure knowing that this site has provided me with informative advice and support!

Thank you, especially Joe Isuzu...


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PostPosted: Thu May 22, 2014 12:14 pm 
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Ok, just read the factory (series 11) diesel manual...could not find "cold start device" but did come to "quick on system" in the electrical part 6D-26.

I suppose the vacuum hose that runs from the injection pump over the front engine top to that switch on the driver's side wheelwell might be connected to this problem...it was out on the wheelwell when I first got the vehicle, cut the bad end and placed it onto the fitting.

Is this part of the device Joe Isuzu was mentioning? Is there something specific I am missing?

How would I disconnect the unit (when learned what that unit is and where it is) and then test?

Thank you


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PostPosted: Thu May 22, 2014 12:56 pm 
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Joe will be along soon to tell you how to check it out. I would bet within a couple days he will respond. The diesels are not as popular here, Joe is one of your best bets for help on this. His real name is Jack.

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PostPosted: Thu May 22, 2014 6:07 pm 
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Luvrv8 wrote:
Joe will be along soon to tell you how to check it out. I would bet within a couple days he will respond. The diesels are not as popular here, Joe is one of your best bets for help on this. His real name is Jack.

Thanks. I've taken a new job where I'm actually working all day long, and I have yet to even visit a non-work site while at work. So I have very little online time nowadays.

I try not to make unnecessary references to IsuzuPup.com, but there are two topics there that are very relevant and I can't re-create them here.

The first one is a great explanation of the CSD (Cold Start Device) from our resident diesel injection expert "Paul". He works part-time at Diesel Injection Systems in Santa Maria, CA.
Cold Start Device (CSD) and what about it?

The second is an epic thread about my performance problem that took years to finally nail down. I'm not sure if this is your issue, but it's worth checking.
Erratic Performance

I don't know a way to test this without some specialty equipment--other than to just remove it. I covered the hole with a cover from the opposite side of a salvage pump. If you remove it, you MUST block off the return line.

Jack

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PostPosted: Fri May 23, 2014 8:26 am 
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Once again I am provided with sage advice via this forum and especially Joe Isuzu (I know...Jack...but I like to say the last name Isuzu).

I'll go review those previous posts and we'll see if the investigative powers can uncover what's what with my little toy!

Again, thank you all for this input.


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PostPosted: Fri May 23, 2014 9:09 am 
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Guys, Just read both of those links on the CSD. Very informative, way beyond my mechanical skills (or lack thereof) however, I think my guru pal can certainly handle this, at the very least he will be able to describe what's what in this injector pump.

My take away from all of this is that what looks to be a simple engine is really not, especially if one seeks to get top gas mileage. Kinda like a big band, you get great music when every player is doing what is expected (and designed) within the sheet music.

So, we'll continue with our major inspection of primary components, then go to those areas we can verify are not performing as designed.

It's all fun, the rainbow at the end of the tunnel is driving this little truck past gas stations at a respectable speed and knowing that you can pass an 18 wheeler on the interstate without fear!

The one element I have not seen is the "black smoke" that those posts suggest are common with a malfunctioning CSD. Leads me to think we just might be ok...well, more of a wish so to speak.

This coming week we are going to set up a day to do the timing belt...under my shade tree!

May have to postpone the trip up north (Dakotas) till late summer when the flying bugs can carry a person off or suck out most of your blood!

Oh, last night my guru wrench said we should also "run the rack" on the engine while doing the timing belt. I asked him what that meant and he said "set the valves" to my wonderment.

Lingo among mechanics, ain't it great!

Thanks guys...


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PostPosted: Fri May 23, 2014 9:38 am 
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Run the rack, really? This is not a Detroit Diesel. These engines do not have a "rack".

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PostPosted: Fri May 23, 2014 7:28 pm 
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When setting the timing, your friend needs to be careful to get a good measurement with the feeler gauge. The rocker ends tend to get cupped over the years, and that makes it hard to get an accurate reading.

Jack

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PostPosted: Mon May 26, 2014 9:17 am 
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Hey, thanks for that info on adjusting the valves...I'll tell him. Seems we have some other "old timers" who when I used the phrase "run the rack" knew it meant a certain brand of engine of which the Isuzu family does not share a similar design. There's a lot of working knowledge viewing these postings! I appreciate that.

Continuing my humor on this vehicle. Yesterday, I had to go to the southern part of town, so decided to take !-25. Wouldn't you know it...this little beast decides to run up to 65mph on my unadjusted speedo (read 70mph) for the entire time with the temperature gauge staying in one place, just south of mid range. No wind, little traffic...go figure.

Maybe it's just getting back to acting normal via the less than 2000 miles I've driven it since being parked in '97. Filled up the tank, put in some additive with cetane...we'll see what the next tankful does.

Only this tank gave about 30.5mpg, less than the first (35.9), but it did have that 100 mile trip to Santa Fe with the heavy winds to go against.

Mysteries abound!

So, that little vacuum line that attaches to the white plastic part on the rear of the injection pump with the line crossing over the front of the engine to the driver's side inner fender well where it fits onto a part which has a wire (sensor/switch?) going into the loom...this unit does what and if disconnected what happens or does not happen that should happen? I ask because I double checked it when looking for that CSD Joe Isuzu mentioned in a previous posting.

Also, in reading the posts previously suggested I noticed this Zexel company brand that offers injection pump rebuild kits. Anyone know what rebuild kit part number for my '81 pump might be, or do I have to locate the data on my pump first, then go for the rebuild kit? Also, is there a simple source to get this kit?

My guru mechanic and I just might want one if we think we're smart enough to tackle rebuilding the CSD, even the pump...challenges are what attract us to such problems; either that, or we are the people the real mechanics dream about for work!

Again, thanks...it was fun knowing the vehicle can do 70...as to why, still a mystery.


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PostPosted: Mon May 26, 2014 9:48 am 
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dakotabound wrote:
Continuing my humor on this vehicle. Yesterday, I had to go to the southern part of town, so decided to take !-25. Wouldn't you know it...this little beast decides to run up to 65mph on my unadjusted speedo (read 70mph) for the entire time with the temperature gauge staying in one place, just south of mid range. No wind, little traffic...go figure.
That's sounding like mine. Note the first word of that topic: "Erratic". It was in intermittent problem.
dakotabound wrote:
So, that little vacuum line that attaches to the white plastic part on the rear of the injection pump with the line crossing over the front of the engine to the driver's side inner fender well where it fits onto a part which has a wire (sensor/switch?) going into the loom...this unit does what and if disconnected what happens or does not happen that should happen? I ask because I double checked it when looking for that CSD Joe Isuzu mentioned in a previous posting.
That white plastic part is the fast idle diaphragm. At this age, it probably does nothing at all. By now, the diaphragm probably leaks. You can disconnect that vacuum line and hook up a vacuum pump to directly to it. If it pulls the throttle arm open, it's working. All it does is brings the idle up when cold, or when the a/c compressor is running (if equipped with a/c).
dakotabound wrote:
Also, in reading the posts previously suggested I noticed this Zexel company brand that offers injection pump rebuild kits. Anyone know what rebuild kit part number for my '81 pump might be, or do I have to locate the data on my pump first, then go for the rebuild kit? Also, is there a simple source to get this kit?

My guru mechanic and I just might want one if we think we're smart enough to tackle rebuilding the CSD, even the pump...challenges are what attract us to such problems; either that, or we are the people the real mechanics dream about for work!
It's a standard Bosch design, so most of the seals are still available. Some people have re-sealed their pumps "at home" but it's not a rebuild. To do a true rebuild, you need some specialized tools.

The Isuzu CSD is NOT a standard component. I don't know of anybody but Isuzu who used this type of Cold Start Device. Consequently, parts are not available and it's probably better to remove it than attempt a rebuild. It can be replaced with a manual CSD (from an old VW Bosch pump), but that requires an almost complete teardown to install. I had this done on mine when I had it overhauled. It now has a VW lever-operated Cold Start Device--and I've never hooked up a cable to it, because I've never needed it. It starts just fine without it.

Any more, and I'll be just repeating what you've already read on the link that I gave you, so I'll stop here. And given that this topic probably has VERY little interest here (as Luvrv8 mentioned), and it's been pretty much a 1-on-1 dialog, maybe you should post follow-up questions at IsuzuPup.com. You'll get more feedback than just from me, because we have a lot more diesel drivers there.

Jack

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