87 R1500 6.2, 196K, I've put about 4500 miles on it since I bought it. It's my first diesel so I'm still learning. I've run algaecide thru both tanks, then replaced the fuel filter. Ran some 911 thru it a tank or so ago. Been running good other than the surge from worn out IP advance (truck sat for 2 years, advance was frozen, then popped free and began the surging).

A few days ago the WIF light started flickering occasionally. Only for a couple seconds. Drained about a cup out of the filter, got maybe a teaspoon of water.

Then the WIF light started coming on 100% on acceleration. Drained about a cup, clear, absolutely no water to be seen.

Then yesterday it came on at any touch of the throttle. Would go off under braking, slowing under 35mph, or at an idle. Truck seemed to have a little more power and its normal 35mph surge (from the advance wear) was noticably less, but seemed to have a slight 55mph miss.

Today it did that for a little bit, then went off and only came on under acceleration. Power seems back to normal.

Looking thru the post it seems the likely causes are
1. Water in fuel (but I drained that)
2. Plugged filter (after 4000 miles? I hope not!).
3. Low fuel pressure due to lift pump going.

I'm starting to lean towards #3 since it seemed to lean out, the light did not come on at idle but got more frequent with increasing throttle or RPM, the fuel looks good, and the filter is pretty new. I've got a lift pump on hand and kind of wanted to swap out the hoses anyway (slowly going thru the truck).

Any other thoughts? Thanks!

87
A few days ago the WIF light started flickering occasionally. Only for a couple seconds. Drained about a cup out of the filter, got maybe a teaspoon of water.


Any other thoughts? Thanks!

It is NOT just a water-in-fuel light. It is also a filter restriction indicator. When the light starts coming on like that, it means you need a new fuel filter element.

yeah, I figured it was a fuel issue, since it seemed to be leaning out. But another filter after only 4000 miles? It's gonna get expensive. Considering $10 per filter, if I have to do one every other oil change, I'd be better off going back to my gasser (one filter every 75,000).

Probably do the lift pump too so any/all junk gets caught now. One less thing to break when it's not convenient.

if your changing that lift pump its gonna be a bag to get out i had to use a 11MM socket and a universal to get it out

But another filter after only 4000 miles? It's gonna get expensive.

It ought to lask 20K miles, not 4K, with good clean fuel.

might take a few filters to clean out crud in tank from sitting. other option is to remove tank and clean it out

might take a few filters to clean out crud in tank from sitting. other option is to remove tank and clean it out

Quoted for truth. Your truck had crud in the tank; your filter did its job, and is now too restricted to keep your truck happy. After sitting for so long, it could easily have enough crap in the tank and lines to muck up a filter or two. Expect the next one to go in 10k miles or so, then you should be up to the normal 20k change interval for that filter.

if your changing that lift pump its gonna be a bag to get out i had to use a 11MM socket and a universal to get it out

if he needs to change the lift pump i'd say scrap the mech one and get an electric LP from a 6.5. just my $0.47($0.02 with inflation :rolleyes:)

damn you dave and your electic pumps lol. probably is a good idea to put on a electric one because if you turbo it down the road it will be alot easier.

its easier to bleed filters and injector pumps too

ill stick to my mechanical pumps now since i spent so much time on that turbo drain adapter plate lol.

You guys know my thoughts, if it ain't broke, don't fix it. I know, I'm wasting kbytes again! Or is it bits? I still have stock diaphram pumps on both my 6.2's. I haven't experienced any problems, especially enough of a problem to get me to plumb and wire an electric pump.

I fill my filter(s) one at a time, start the engine, purge it, change the next one. No purging or priming problem. I never run it out of fuel, I'm very careful about that, you pick up all kinds of crud when it sucks the last of the fuel out.

I replace my fuel lines when they become brittle, chafed, cracked, etc. I inspect them on regular services. No problem.

I know, I know, "Old Guy"! I'm still tryin' to figure out the transition from a four-track to an eight track tape player.

The only reason i wired an electric one in was because i got it for $10 from a friend. the relay and wiring was kicking around the garage so that didn't cost me anything.

The pump's plumbed in right where the old mech one was. The mech one was leaking diesel into my engine oil so i didn't want to put another mech back on.

Had to refill the tank Monday, and guess what? All the way home yesterday, and the way in this morning, 70 miles of no WIF light! So probably did pick up a slug of stuff out of th tank and it had to work its way thru the system.

I ran the algaecide about 3 tanks ago, ran them to E on the gage, then ran 911 and a fresh load then drew down to E again. I find if you empty the tanks regularly then you get the crud out regularly and don't get that big slug of crap.

But, in the spirit of smartness, I'll change the lift pump and filter this weekend. It's not that big a deal to me, I got 2 brand new LP's with the truck (I think the PO mistook the miss and surge for LP when it's IP) and also a free filter. I don't bother filling the filters, I pop them on, remove the bleed plug, cover the hole with my finger, then apply my vacuum pump to the hose on the bleed port. When it stops bubbling I'm good to go, might get just a skip but is happy to restart.

Thanks for all the suggestions and direction. Now, if only I could find a good IP cheap....

I ran the algaecide about 3 tanks ago, ran them to E on the gage, then ran 911 and a fresh load then drew down to E again. .

If you DID have problems caused by diesel-bacteria or algae, the pickup screen inside your fuel tank it probably close to plugged. Adding algaecide only kills the living organisms but does NOT remove them.

I've had to pull out several of my pickup screens in the tanks and scrape off the black sludge (from the dead stuff the algaecide killed).