Another hard cold start issue

[greasemonky]

Hi guys, new to the forum here, just signed up but been reading for a couple of weeks. I have just bought a 88 7.3 a few weeks ago (see sig). I am having cold starting problems. It will start after cranking for a minute or so and then runs fine (except a slightly rough idle) and starts fine after warm.
Here is a list of things I have check and or replaced:Glow plugs are new(motorcraft) with a new relay and I run a #4 cable to the relay with a manual switch, New return line kit,caps,orings,etc. Also I have changed injectors with a set that I know are good(pulled from my Dads 80k mile truck).
The check valve in the filter head is bad and I know this will cause cold starting issues so I put a small cut-off valve there and shut it off at night for testing purposes(I have a new one on order) still hard to start in morning. I have checked every fuel line on the truck for wetness.
When I first got the truck it had leaky caps so I replaced with the new kit, I still was having leaking issues around the caps. I had to clear out the return line down to the tank selector valve after that all dry. Must had some crud in there.
Also it has a slight rough idle almost like an intermittent miss in a gas engine. Its not bad but I know its there so it bothers me. I figure it's all related to the cold start issue. Probably air but where it's coming from is the mystery. There are 2 other IDI's here on the farm so I know what should run like.
With the mileage that the motor has i thinking maybe the IP is the curpit. I didn't get any information from the previous owner if the IP has been replaced. It does seem dry though and the motor has plenty of power I will add.
Any suggestions? Thanks in advance.

 

[Compu Doc]

Check to see if the lift pump is working. This can be determined by pulling the fuel filter when the engine is cold before starting. If it is not completely full it's probably the lift pump that is bad. With the filter still off have someone crank the truck to see if your getting fuel flowing through the filter head. If not then it is a bad lift pump. Also you could have the water separator leaking leaving the fuel filter half full by the time it has sat overnight.

Take a clean piece of pa[er and place it under the bottom of the fuel filter. Check the paper in the morning to see if it has fuel on it.

 

[OLDBULL8]

Do you push the go peddle in to set the Hi idle solenoid after you turn the key on? That helps with cold starts. It will Hi idle 950 RPM until the pass head reaches 120 degrees then slo down to 650 RPM.

 

[greasemonky]

The fuel filter is the old style. The previous owner had put it on. There is no bowl on the bottom that the sensor hooks to, just a drain screw on the bottom of the filter.
The high idle does not work, the PO had put in the wrong sensor in the head with a one wire ***( yes I said ***). He had the water sensor wire hooked to it and the water in fuel light was staying on. Took me a couple of days to figure that one out. Currently the two wire plug is not hooked to the temp switch sensor. Will the parts store have that switch or is it a dealer item?
When cold I give it a little pedel when starting after it starts I can let off and it will idle fine except that little miss in it. Cold or hot it will miss ever so slightly. I can bring up the rpms a few hundred and the miss clears out. Runs down the road just fine with plenty of power.

 

[greasemonky]

Forgot to mention that the batteries are new and the starter really whips it over fast.

 

[Compu Doc]

One word of advice. Do not crank the truck longer than 30 seconds. If it does not start then wait two minutes before cranking again. If you don't that starter will not whip it over really fast and you will find yourself replacing it.

Check the fuel filter in the morning to see if it is full or half full. Then do as I said above. If the fuel pump AKA lift pump is bad the truck can still run but the injection pump will not last long.

 

[omedrud]

one thing i have found in my 90 f250 idi is that you can take a can of starting fluid and spray around at different lines and if it picks up then you found your leak i know your not suspoised to use starting fluid to start a truck but also check you water seprator my water saparator would just drip when cold but when it was hot it would not so i fixed that and still no luck it still had a kinda miss to it so i did some more checking around with starting fluid and finaly found it was a cracked injuctor line not a real big one it was small enough to let air in the line but not let fuel out so i changed the line and presto it went awaysome of the smallest things can cause havoc and not let it run right and one bubble will cause a diesel to run like poop for two the three min so any way best of luck

 

[greasemonky]

Thanks guys, I'll check the filter before starting this morning. Also anyone with a manual GP switch? How long holding current to the GP. So far I stay about 10 sec when cold. Is this enough or too long? Temp is in the upper 50 low 60's right now in the morning.

 

[omedrud]

Thanks guys, I'll check the filter before starting this morning. Also anyone with a manual GP switch? How long holding current to the GP. So far I stay about 10 sec when cold. Is this enough or too long? Temp is in the upper 50 low 60's right now in the morning.

ya thats fine 10 secs is good up hear in montan some time what ill do is ill cycle them my glow plugs are not hooked up to a switch so ill turn the key on and then turn it off and then back on and then try to start when its in the low 30 to high 20s ill do that but a good way to know is if your holding them on for ten secs and when you start it and you get lots of white smoke you didnt hold them on for long enough you can hold them on for a max of 25 secs but some times when its relly cold try cycleing them best of luck

 

[jonathan]

when its running lossen each injector one at a time if the idle doesnt change that would be a bad injector aka a miss

 

[greasemonky]

Ok, it missed with the old injectors and with the replacements both. I figure I can eliminate those from the factor. Raining this morning so I didn't check the filter to see if it's full. I got some clear hose that I'm putting on #1 to filter head. I'll post results.

 

[icanfixall]

So you say the engine continued to have the miss after replacing the injectors.... Probably injection pump time. Thats the only item that has not been replaced yet. Becieds the lift pump.

 

[greasemonky]

I was afraid someone might suggest that. Well it leaks oil from the gear cover anyway. Can mark the gear somehow from the gear cover front plate and just replace the IP If nothing moves it would stay timed, theoretically?

 

[TWeatherford]

Nope it won't be timed. Marks only tell you where that IP is timed relative to that pump and engine. New IP and timing will be different. That said an improperly timed by ear pump will still run way better than a worn out IP that is properly timed (in my experience). With a new fuel system mine starts great. -3 F is the coldest I've seen and it was about 5 seconds cranking and fired up, that is with conventional 15W40 in the crankcase, and not so new starter or batteries. I run a manual glowplug setup and love it. I only go about 5-7 seconds in this weather, 10-12 below freezing, and 16 max in the bitter cold. That way I only ever will have to replace the glowplug solenoid (never the brain part), and as a matter of fact I've been running a starter solenoid for a while now and it hasn't had problems. People here told me it wouldn't last more than a few starts but its been fine so far. Spare is in the toolbox though, just in case (another boneyard fender mounted starter solenoid).

You've replaced about everything that can be a problem. I would suggest you go over everything carefully and look for leaks in your fuel system. Just because its new doesn't mean its good. You could even have a pinhole in your steel fuel lines somewhere. The reason I say this is because it starts after a minute of cranking, and then starts well after that.

Next step I agree with the others, lift pump might be suspect. However if it was hard starting because of a bad lift pump I don't see why it would fire after a minute and then do well while warm. But at the age and mileage you've got a new lift pump isn't a bad idea.

Next I would say injection pump, though I'd probably hold off as long as you can since you say you've got good power.

 

[jonathan]

you are suppost the replace the the ip and the injectors at the same time