Did 400 mile today into South West Wales to drop of my house build reciepts for a tax accountant to process my tax reclaim... we get 20% Vat back on new build house materials costs, my truck must have smelt the £££ as on the way back in lockup OD accelerating a little uphill engine seemed to just stop for less than a second but then back to normal with a clunk as the trans was driven again.... that is the best I can describe it,

just like a manual trans and coming off the throttle and then straight back on it , I hadn't got the Modis with me so couldn't check anything,  but no codes on dash, I don't think the trans is dropping out of drive  as engine revs do not rise in fact all engine noise stops, I don't think it's fuel as there is no indication of it happening, no misfiring or rough running just off then back on, without the VP does odd things if FP is low as I did see 7 ish psi a few times today but I don't think it was the same time as this problem happening, this happened 4 or 5 times on the way home ??

 

I have to use it tomorrow but I'm going to take the modis and monitor the apps first and then check the whole lot while driving.... sounds electrical to me

Check the automatic shutdown relay; it may be going bad.

You can also give the wire harness the old tug and shake test with the engine running.

Edited August 29, 20195 yr by IBMobile

Thanks I'll check that relay first thing tomorrow, the apps isn't very old not a Timbo but to be fair it didn't feel like the last one that failed, that felt like the throttle position had changed not just been switched off which is how it feels now so the asr as you suggest explains it better, I'll start with that

I have had a happen a good while. Fuel filter stopped it the first time. The other times were with in intank pump loosing pressure. I put a booster pump on it and it stopped. 

 

The issue is very much as you describe, almost like the engine shuts off for a split second then keeps right on going.

When my truck had only around 35,000 miles, it did this once exactly as you describe. Knowing about weak factory lift pumps and seeing fuel pressure had gone down from normal, I pulled over and changed it within about 8 miles at a friends house. I had another factory lift pump with me for back up. In those days I thought having the Big line kit with the factory lift pump on the frame was enough to make everything okay. 

 

Today both trucks have big lines, big Draw straw, and Raptor 150's with a pre filter in front of the lift pump.

Edited August 31, 20195 yr by JAG1

I drove maybe 300 miles yesterday very steady and it is fuel related, any time I had to pedal it a little  for a hill it was bucking really bad, I did swap the ASR for the wiper relay before I set off so it isn't that.

It has a really cheap inline prefilter which was fitted by the PO so I am going to check that first, Caterpillar use a similar filter so I have those and the truck has a cat main fuel filter on it which I fitted so got that covered.

At best I have to drop the tank and bite the bullett and do the job right, funds might be tied up on a 5th wheel upgrade so may have to relocate the FP to the frame and go big line for now even though I don't like it

I think what happens when inadequate fueling is the VP cavitates and may cause harm to internals. I hope your okay on yours.

Edited August 31, 20195 yr by JAG1

me too... it appears to be ok for now, and since it started doing this it's also been in a fair bit of stop start traffic so on idle fp is back to 15 + and fuel is hopefully going back to tank...

No excuse really on my part I should know better but I only fitted the gauge a week ago or so