Engine runaway

DoubleL · Feb 22, 2015

My new build is up and running BUT when I give the throttle a good blip that will drive rpm above about 1700 rpm, when I let off pedal the rpms continue to rise beyond redline. I have to shut key off to get it to come back down. While driving it feels like cruise control and braking brings it back down to normal.

What I've tried cuz I have 2 1999 trucks is; pcm swap with and without tunes, I have different tuners on my hydra chip, and pedal assembly with tps on it.

Anybody got some ideas for me?

pullandpray · Feb 22, 2015

The fact you can shut it off probably means it's electrical. Was there massive amount of smoke or anything usual like that?

DoubleL · Feb 22, 2015

No unusual smoke after these events. Truck had lowered compression so there seems to be a constant haze sky far. Previous owner had the haze in colder weather also. I thought electrical too, reason for pcm and tps so far. But now what? Maybe ipr sticking?

pullandpray · Feb 22, 2015

Do you have anyway to monitor it?

DoubleL · Feb 22, 2015

Just auto enginuity but it only logs every 2 seconds. Hate that about it, been wondering if my version is just old and newer ones are better?
I sent a log file to my tuner and he noticed it was calling for fuel when off the throttle, so we thought pcm, well that wasn't it. I decided to try tps myself just because it's so easy to swap.

PsdPullerJr · Feb 22, 2015

Mine did the exact same thing last summer when I put the motor back in. After (I'm guessing here) about a dozen start ups and driving prob 20 miles fairly aggressively, it never did it after that. I never did figure out why, I just figured it had air thru out the whole motor since the injectors were out along with the pan and front cover removed.

DoubleL · Feb 22, 2015

Ya I've been thinking and praying its air in system, just pretty cold around here still to be brave enuf to risk breaking down too far from home lol. Highway is 4.5 miles.

DoubleL · Feb 22, 2015

Ok new problem that's possibly related... I went out and couldn't resist a 4x4 boosted launch. Well must of raised icp highest yet cuz it blew my oil line right out of back of the hpop! It's really my fault, I mildly stripped the threads when installing the gen3 but thought it tightened up good. Guess I was wrong.
So how do I fix this? The fitting in there is a 6MB-8MJ90. My pump on truck is a T500 with the gen3. I noticed my SRP1.1 has a much larger plug/threads at back of pump. So my current thought is too enlarge the current hole and threads to match the srp1.1 then try to figure out the fitting needed which I hope is a 8MB-8MJ90. I'm not sure on fitting though.
Any ideas how to fix my screw up on pump?

psduser1 · Feb 22, 2015

Srp s use a #8 orb fitting. If the is enough material to drill and tap to that size?

DoubleL · Feb 22, 2015

Pretty sure There is? It looks like same housing just been enlarged there on the srp1.1.
What other options do I have? I thought maybe I could just go a little bigger then try to figure out the plumbing. Swamps uses hard stainless pipe so I'm gonna have to change that I suppose.

psduser1 · Feb 22, 2015

The hard lines shouldn't need to be changed, just use a #8 orb x #6 Jic fitting at the pump. Assuming, of course that the hard lines are 3/8"?

DoubleL · Feb 22, 2015

Ya that's what I'm thinking at this point, except current line is #8 jic. So 8orb to 8jic.

Is this the same as your orb you mentioned? 8MB-8MJ-90degree. Current fitting is a 6MB-8MJ-90

Does anyone have one laying around? I'm out in the boonies sorta. Im gonna see what swamps does for guys with larger hpop fitting on Monday. So for today I guess I'll pull some pumps.

psduser1 · Feb 22, 2015

DoubleL said:
Ya that's what I'm thinking at this point, except current line is #8 jic. So 8orb to 8jic.

Is this the same as your orb you mentioned? 8MB-8MJ-90degree. Current fitting is a 6MB-8MJ-90

Does anyone have one laying around? I'm out in the boonies sorta. Im gonna see what swamps does for guys with larger hpop fitting on Monday. So for today I guess I'll pull some pumps.

I'm not familiar with all the part/model numbers, offhand, lol. Ive got a parker fitting book at the shop,for reference. I can look here in a bit.

pullandpray · Feb 22, 2015

Common man, just get a used pump and put it in. I mean your talking possible engine fire if that fitting blows out. Just buy a core pump and slap the gen 3 on it. It will flow plenty. At the very least call terminator and see if he recommends that. I personally wouldn't risk a built engine and possibly a truck with tapping a cast case.

DoubleL · Feb 22, 2015

Your probably right about being safer, but it looks like I can just easily bore it out as Stealth did. I would like to run this T500 since it has less than 2000 miles on it. I measured with a mic and the housings are identical. Not sure the thread size yet of the 8MB.

Arisley · Feb 22, 2015

Maybe bore it out, put a helicoil in it and run the stock fitting.

DoubleL · Feb 22, 2015

Looks like stock thread size for 6MB is 9/16 - 18 and if I go to the stealth srp1.1 size it's 8MB and 3/4 - 16. I think if do this it would be best to bore out the hole and go with the next size up MB (orb) fitting which is 8. Reason being I've found they make same fitting to fit my lines in the 8MB and 90 degree fitting.

psduser1 · Feb 22, 2015

DoubleL said:
Looks like stock thread size for 6MB is 9/16 - 18 and if I go to the stealth srp1.1 size it's 8MB and 3/4 - 16. I think if do this it would be best to bore out the hole and go with the next size up MB (orb) fitting which is 8. Reason being I've found they make same fitting to fit my lines in the 8MB and 90 degree fitting.

Sorry, I completely forgot to get a part # for you today. If you are dealing with a hydraulic store, they can set you up, based on #8x#8.

DoubleL · Feb 22, 2015

That's ok I found one on a site called KSC direct. Gonna see what Swamps does for guys that have an SRP1.1 or any other pump that has the #8 size at back of pump.