96 Summit X 670-dmp....help

[Whitefisher]

I just bought a 98 Summit X 670 was on my first ride got 7 mi. poped then died,, fiooded out, pulled plugs dried. cleard cyl. plugs back in,starts right up, idles giveit gas it dieds ,,, flood again ,,,,over .. great spark..fresh plus fresh gas.. this is a d.m.p . carbs.. ran great for 7 mi..........help..?????????/

 

[AGL4now]

Someone may have change the "Jets".

 

[keh]

Carbs likely need some work. Lots of time the needle and seats are leaking. Replacement is fairly easy and gives you a chance to check the oil pump setting as well. If i recall correctly, this sled will have a rotary valve behind the carbs. I had one that would flood immediately when you touched the throttle. Several mechanics worked on it before I found one who immediately checked the rotary valve cover o-ring. It had been pinched during an overhaul. 30 minutes and a $3 o-ring later, it was back in business.....

kevin

 

[Paul H]

It would be worth posting on dootalk in the zx and earlier chassis forum, plenty of guys over there that run 670's and know the ins and outs.

http://www.dootalk.com/forums/forum/4-mxz-legend-summit-grand-touring-formula-etc/

If it idles fine but dies when giving it gas could be that the main jets were richened up, or the needles were richened up. I'd suggest finding out what the stock jets, main jet needles and air screw settings are for the carbs, confirm you have the right jets, main jet needles and needle settings and see if the needle for the float needs replacing.

 

[AKDoug]

Idling fine, but falling on it's face when throttle is applied is often indicative of water in the fuel. If that isn't the issue it could be very well that the DPM has failed. That machine is one of the most complicated machines around to trouble shoot. There are issues with the float arms in the carbs (don't park pointed downhill), issues with difficulty starting (three pumps of primer only or it will flood), issues with spark plug caps, issues with the DPMs. These machines absolutely RIP when running right. We have one with nearly 8000 miles on it and I've had a running love/hate relationship with it since I bought it. My kid has it now and I have an evil, wicked, smile every time he has the hood up..I figure it builds character.

The DPM operates by measuring temp (if I remember right) and barometric pressure. With this data it applies vacuum (the pump is under the engine) to the float bowls to lean out the carbs from base line jetting. This machine runs absolutely HUGE main jets and the DPM leans down from there. When the DPM fails (and it will) the machine defaults to the main jet settings. That's a good deal because you won't get a lean burn down engine, but REALLY bad if you need the machine to run at 30F.

We removed the DPM on ours (that story in a second), plugged off the vacuum ports on the carbs, rejetted by very careful trial and error, and used a Vari-Flow (no longer available) to control jetting.

When my DPM system failed I was in the worst possible situation you could have. I was at 4000' altitude, 34F temps, and at the bottom of a powder filled bowl with no way out but UP... I could not get out of there because the machine wouldn't run past 1/3 throttle. It was so steep we couldn't even tow it out. I was PISSED. My solution was to take the largest main jets available in the group (a set of 180's) and remove the stock 340's... a drastic 16 steps in jetting. I plugged off the vacuum to the carbs and away I went. My theory was, the engine would live long enough to get to the top of the hill, after that they could tow me back down to the trucks with my blown engine. Funny thing happened...that machine ran better than it ever had and it never did blow up.

The internet is FULL of info on the SummitX 670 because it's such a pain in the ass machine. There is almost no way I can diagnose your issue online. Frankly, I have forgotten 90% of the fixes I did to that machine because it's been 5 years since I worked on it regularly.

I have a soft spot for this machine because it took me places few could go back in the early 2000's. My adventures on this machine were an important part of my life and I will always look fondly on those days...even the ones (many) I came home on the end of a rope. It's a good thing too...because there are many days I want to crush it with my backhoe.

 

[mod elan]

Main Jets-350P/340M
Needle jet-224/AA-8
Pilot-55
Needle-7ECY1 #2 position
Air screw-2.25
Idle 1700

Remove the float arm and pound flat. You will need to clip the ends to fit inside the bowl. This will lower the float level and help with flooding.

Run Premium fuel. They do not like to be run hard on regular.

If the Digital Performance Management has failed I would suggest eliminating it and installing an ATACC.

 

[Whitefisher]

Ok fuel system working...... found intermedeit spark ., new dess key.. same thing happen. checking all plugs ?

 

[AKDoug]

Spark plug caps on these things can be problematic too. Change them out along with new plugs.

 

[saint_nick3]

Also, those 670x's like solid top spark plugs. Mine ran like crap with the thread on style caps. The BR9ES spark plugs come in two flavors, solid top or thread on. Make sure you have solid tops.

 

[Bullelkklr]

I had a bad wire at the voltage regulator that gave me fits until I replaced the regulator. The bad spot in the wire was not physically detectable because it went right into the "glue" that encapsulates the voltage regulator electronics. Check voltages on the coil too.

The DPS keys were known to be troublesome. You might try the ATACC like mentioned above. My 96 uses the HAC instead and does not have the DPM - even though the 1998 block wants to see it, it still runs, but the deletion of the DPM will require a different key or deletion of the key if I remember right.

+1 on the doo-talk forums

If you decide to crush it, can I have your chain case and gears if it has reverse????? I cratered mine last year....

I put a 98 motor in my 96 using the 96 electronics- it indeed RIPS, I did tank a piston the first year I got it running (2 years back) - not exactly sure what happened, but I got antifreeze into the jug (couldn't see any bad spots in gasgets etc....).

 

[Bullelkklr]

I found it by implimenting an "aggressive & thorough" wiggle test when running (which was seldom and intermittent - significantly compounding my trougleshooting difficulty).