hard starting...after all these years

["Mad Max"]

... after 130,000 miles of faithful service, the last 37,000 with me, my '93 is finally showing some signs of 'age'.

For the last week or so, every morning's start has been difficult, requiring several seconds of key'd starter engagement to get it to run. Blows some white smoke until it fires, then runs just fine. Thought it was a bad lift pump, replaced it (and fresh fuel filter for good measure) no joy - same issue.



So it seems to be 'losing' fuel overnight... but to where? and there are no visible leaks or even sweating from any fuel systems. I'm thinking something internal in the IP has finally sprung a leak, but what?



Can the IP's develop an internal 'leak' (bad seal, etc) without any visible signs on the outside?



Once it's running it runs like it should - full power, smoke is proper black color, etc.



Thoughts?



- Sam

 

[cerberusiam]

With the whilte smoke like that sounds like injection timing is way late until you spin it for a bit. The case pressure relief valve controls a lot of that and they stick, get crud in them, etc, and create just what you are describing. There are other things internally that will slow down the timing aalso.



Either way sounds like it is time for a pump refresh.

 

[Greenleaf]

The shaft seal can leak. There can be an air leak in the pickup (suction side) of the fuel supply system. The lift pump can leak internally.



One of my trucks began to do that and it was a very small leak at the injection pump. I had to prime the system with several pumps and then it would fire right off and run properly. I eventually had to take the pump down at about 322,000 miles and replace every seal.



I worked on another one that developed an air leak in the suction line. Leaks no fuel out, but draws in air. You couldn't prime the system properly and it would stumble time to time when running.



Sounds like you have issue "A", or a combination of the two.

 

[JLEONARD]

The white smoke is unburned fuel. When my lift pump was going it would spew some white until it fired and cleared.

I was getting SOME fuel to the injectors and into the cylinders but it was not enough to fire... hence it went out the exhaust.

So it sounds to me like you are getting air from someplace. You can pressurize the system via the tank tank by using an air gun and a rag to loosely seal the filler tube. You only need a couple psi to run your test. If the leak is between the tank and the lift pump this should pinpoint it for you.

If you don't find anything there you'll have to look at what Scott said on the injection pump.

 

["Mad Max"]

if it is sucking in air during the start cycle is it also then sucking in air while it's running? It runs same as before once it's rollin'. I'm gonna check the oil and make sure it's not contaminated too. Is it possible to push fuel out the front shaft seal? I wouldn't think so but I'm just surfin...

 

["Mad Max"]

likely I'll do a vacuum check on the fuel line - trying to determine how. May even install a permanent fitting just for that for future possible similar problems. now to figure out how to do the vacuum test... . and with what tools... . ?



And while I'm doing that..... I'll likely rebuild the pump. But maybe I should cure this problem first before I generate another...

 

[FourBarR]

i am not a 12 valver however I have read here of problems with a fuel return hose at the left rear of the engine that will not leak fuel but will suck air when the engine is shut down. Maybe a 12 valver will chime in with more info.

 

[cerberusiam]

if it is sucking in air during the start cycle is it also then sucking in air while it's running? It runs same as before once it's rollin'. I'm gonna check the oil and make sure it's not contaminated too. Is it possible to push fuel out the front shaft seal? I wouldn't think so but I'm just surfin...

As long as the fuel pressure past the LP is good its probably not a leak in that section. If it is a leak prior to the LP then it won't prime right. However, every problem like that has shown issues when running also.



If the sytem is not priming there is little smoke as fuel is not being injected. If its pumping white smoke on crank and not firing the injection timing is way late. That almost always ends up being internal pressure not high enough to fill the fuel port correctly until pressure builds. The last 3 problems with these sytems unding up being th einternal bypas\pressure valve either not sealing or fuzz clogging it.



Hope you find the issue with little hassle.





Just think, if it was a 2nd gen it would probably be the VP. If it was a 2rd gen it would be injectors. Either one of those will cost waaayy more than rebuilding a VE. :-laf

 

[DVolk]

My 92 cranks a few times when its cold and smokes after fir up for a few when could you rev it up and it clears . It idles a littel slow when cold as well but when its warm it runs fine with no issues . I think mine has the timing not correct as a few years ago the pump loosened up and backed off a littel , i noticed it by a oil leak and on a bumpy road

it started burping when it was running , id like to cure the problem my self only clue would be a retime and maybe a pump rebuild , lift pump was replaced a year or so ago still has the issue but got to the point it wouldnt start though

 

[JLEONARD]

I have read here of problems with a fuel return hose at the left rear of the engine that will not leak fuel but will suck air when the engine is shut down.

Very common in marine applications actually, but I have never run into this in the truck application.

 

[DVolk]

If this is a possible cause then a can of WD40 or ? sprayed on it should find such a leak then but then those stock plastic fittings i could see the orings going south causeing a issue to bleed off is that the issue ?

 

["Mad Max"]

well this morning I tried the simplest of possible cures - I opened the hood, grabbed a decent chunk of wood, and politely whacked the KSB and toaster relays. The truck... of course... started just about normally .



What is interesting, is on initial key-to-run, the toaster relays 'click' and the voltmeter dives like normal - ( wait ) - [start] - rattlerattlerattle... . but then when I expect the relays to click back on and the voltmeter to dive again for the usual minute or so... ... it isn't. I'll hear the 'click'... but no needle dive... . ??!!?? It's like the relays hit the first time, but not after the truck is running. Swell - I hate the weird ones.



Now... once it's running I've really no real need or desire for the toastes to do its thing, but it just buggs the heck out of me when I expect the electronics to do one thing same as been for years and then one day, they don't.



So, gonna see if the problem persists, then I'll confirm/deny the electrical possibility, then if successfull I'll press on to check fuel. Fortunately, none of this is a show-stopper, and dat's good.



- Sam

 

[JLEONARD]

Sounds like it's time to clean the connections including grounds.

You don't want to be done do you?

 

[HHhuntitall]

well this morning I tried the simplest of possible cures - I opened the hood, grabbed a decent chunk of wood, and politely whacked the KSB and toaster relays. The truck... of course... started just about normally .



What is interesting, is on initial key-to-run, the toaster relays 'click' and the voltmeter dives like normal - ( wait ) - [start] - rattlerattlerattle... . but then when I expect the relays to click back on and the voltmeter to dive again for the usual minute or so... ... it isn't. I'll hear the 'click'... but no needle dive... . ??!!?? It's like the relays hit the first time, but not after the truck is running. Swell - I hate the weird ones.



Now... once it's running I've really no real need or desire for the toastes to do its thing, but it just buggs the heck out of me when I expect the electronics to do one thing same as been for years and then one day, they don't.



So, gonna see if the problem persists, then I'll confirm/deny the electrical possibility, then if successfull I'll press on to check fuel. Fortunately, none of this is a show-stopper, and dat's good.



- Sam

You know, I had an employee that was much the same way..... just a whack on the back of the head would get his brain started..... same kinda RATTLERATTLE sound you describe every now and then... .



Funny if it's smoking... . I'm thinking the fuel shutoff solenoid isn't opening/opening slow or internal pressure is way low as stated above... ... Could be that it didn't lose prime THIS time? Have you tried starting it with the throttle down a little?



Hmm, I'd also check the fuel lines for a loose clamp or a lot of cracked rubber. Those suckers will suck a lot more air than you think. My '92 Furd would lose prime at the wierdest times, usually when I really needed it. Turns out, when I transplanted the Cummins, I used just regular fuel line for frame to block jump, and after 4 years, it decided it needed to quit. It never leaked fuel externally, so I was stumped for a few hours, until I applied some vacuum(or removed atmospheric pressure, however you want to look at it!) and it started pulling some foamy fuel fumes up through the line. Made me go, "Gee. That was simple..... once I found it. " Some new line and she runs as good as ever. New high pressure barrier-lined fuel line, that is. (I also did the return line at the same time, as it's P-pumped)

 

[Greenleaf]

My 90 starts hard now. I have to throttle up the engine when I turn it over or it will take quite some time to fire-off. It often runs really slow right after I start it, unless I use some throttle.



It all began when I changed out the lift pump. I upgraded from the OE diaphgram to the Carter piston pump. I suspect that this piston pump won't hold the fuel inside the low pressure fuel supply line.

 

[cerberusiam]

My 90 starts hard now. I have to throttle up the engine when I turn it over or it will take quite some time to fire-off. It often runs really slow right after I start it, unless I use some throttle.



It all began when I changed out the lift pump. I upgraded from the OE diaphgram to the Carter piston pump. I suspect that this piston pump won't hold the fuel inside the low pressure fuel supply line.

You changed its comfort level with the piston pump and its rebelling, like a teenager. :-laf The piston pump doesn't seem to leak back on mine.



I messed around for 2 months trying to find a steadily worsening fuel leak. Finally figured out the fuel heater was working loose a bit at a time. Never had a slow or hard start or any running problems. Pretty sure as long as there is fuel in the pump and the line at least to the filter, and the pump internals are good it will fire on the 1st or 2nd cylinder up.



The case relief\return fuel valve and the KSB with both cause starting and running issues when they fail to function correctly. I have found fuzz in 3 pumps that caused the problem. Never had an issue with a fuel shutof either, must be lucky.



The worst hard start problem I saw was when 2 of the IP mounting bolts fell out and the 3rd nut loosened. Pump timing is severely affected when it can arc thru the whole timing range freely. Still have NOT figured out how loctited studs with crush nuts can spontaneously loosen like that.

 

[DVolk]

thats kinda what mine does but did it before the lift pump install though any one have ideas ? with the running slow ? bad ksb ? My 92s pump loosened up like that as well , i wionder if my fuel heater is getting loose id check that if i could figure out were that is ?

 

[Greenleaf]

Git that durn fuel heater off of there. What a troublesome feature. That and the wonderfully designed factory filter... ... ... ... . WITH A BIG HOLE IN THE BOTTOM OF IT!!!

 

[HHhuntitall]

Fuel heater is held to the bottom of the cylinder head above the filter by the center threads, which work like a bolt to hold the heater up to the head. It unscrews after you remove the filter. I believe the center hole is 5/16 or 3/8 allen head through the center threads? I'll be corrected on that here in a minute..... Also, didn't some of the heaters begin to leak fuel through the wires? Or is that just on the 2nd gens?



Greenleaf, have you seen the filter without the hole in the bottom? Not sure I like the idea of not having a water drain... ...

 

[DVolk]

I had to go with out the drain on my burb project , how ever you can get the fuel filter with a built in fuel drain as well through eitherNapa or Wix /Hastings as well possibly Fleetguard its the same filter but is for tractor applications .

So on that fuel heater you just take it off and but mounting stuff back on and the filter goes back on ?