7.3 IDI slight update..

[Brad Gyde]

Ok, so a few days ago I asked what would make my truck do the things it's been doing (hard starting was one of the issues).. I wasn't looking for hard starting solutions then, but I am now.. I've done everything I can think of at this point.. And tried most of the hints from last time.. What I've found so far:

Turns out one of the 10 month old batteries was junk (so as the girlfriend says, it matches the truck LOL).. I got my battery warrantied, no troubles.

I talked to my diesel repair man Friday, he advised adding lubricant to my fuel and see if that helps solve my fast decel stall issue.. He also advised me to change out my return line check valve to help cure hard starting.. turns out yes, the old one appears to be bad, but the new one seemed to change nothing noticeably. He said it was common for fuel to bled back through the return, and with the old one, I'd say that could surely have been happening.

I have checked my glow plugs, controller, and glow plug harness per the manual I have.. All check out fine, per the book.. (but I have a brand new set of glow plugs in possession.. just can't see putting them in if the old ones check fine)

I HAVE NOT installed a check valve in the supply line, per the advice of Juniur last time, but the check valve will be here tomorrow, and will be installed, unless I can find another solution to the hard start problem.

Fuel leaks was another thing I was told to look for.. I found a small drip Thursday, so, I popped off the line, replaced the rubber "grommet" and now the leak seems to have gone away.. PERFECT! See no other locations showing visible signs of leakage.

But, if the truck sits overnight (or say 7-8 hours) it's not going to start without a fight.. It'll crank and hit once or twice right off the bat, then nothing.. then finally, I'll get visible smoke from the tail pipe, then eventually (usually after cycling the plugs one more time) it'll hit a couple times, start, big amount of smoke, and it will rev quite high, run rough for a minute, then level out and run fine.

I've decided it is likely a fuel problem.. Sound right? At this point, where should I begin to look? Is there a way I could slightly pressurize the fuel system to check for leaks? (I have a fuel cap we made up years ago to pressurize a tank in a combine that would lose it's prime sitting all year, give it 5 lbs or so, crack a injector line or 2, wait for fuel, then would be good to go)

I've made this post long enough.. any questions to what I did testing wise, I can explain.. Open to suggestions on what I might have missed.. Or what else I can try.. I've done just about everything possible per the book, nothing seems to change. Thinking I either have to be losing prime somewhere, or the IP is going.. but if that were the case, seems like I'd have troubles all the time, not just starting.

Thanks in advance for reading yet another novel.. And sorry for my testiness last post.. These things seem to get way off in outer space, and that usually don't help find a solution..

Brad

 

[GordoSD]

Is that hugs amount of smoke white or black, or gray?

 

[JDseller]

Your problem is the fuel is bleeding off while setting. These Fords where bad about doing this. The return fitting/boot on the injectors have two orings in them that has to seal on the injector or they will leak air. My son has a Ford and he has to replace these every few years. There is a complete kit that is the fittings, o-rings, and new fuel lines. It is not that high
Kit on Ebay 19.95 7.95 shipping

 

[Brad Gyde]

Gordo,

From the seat, watching in the mirror, it's almost like it looks white, then works to a medium grey.. The smoke will only last 10 seconds or so

I have a small exhaust leak, and the last few days while diagnosing, I have been starting from under the hood.. I'll see a small amount come from the manifold/y pipe connection, and that looks more white, and has the typical diesel exhaust smell.

I believe white is supposed to indicate a lack of fuel, correct?


JDseller: I can't recall this second if it was last year or 2 years ago all the caps, lines, and o-rings were new, but I will take that into consideration. I believe I have a complete set of new o-rings for said caps.. I bought a set when I had the injectors popped, then shortly after someone gave me a set they no longer needed.

Thanks so far guys.

Brad

 

[Allan in NE]

What JDSeller said.

And oh yeah, find yourself a new "diesel repair man".

Allan

 

[locojim]

My mechanical fuel pump was pumping but bleeding off when the truck set a while once..very hard to start then..But that wasn't the cause of my hard starting issues...I don't know what my problem is either but since its a work truck my solution has been to give it a little shot of either after the glow plugs run..
93 F450 with a factory turbo and have been starting it on either for 4 and a half years.......remember-a little shot....

 

[Sam from WA]

You might try unhooking the mechanical fuel
transfer pump and put an electric fuel pump on.
Wire the pump so its pumping fuel anytime the key
is on, I grabbed power for mine off the shutoff
wire for the injector pump (its the one with the
two bigger wires on the side of the injector
pump). I took the mechanical transfer pump out of
the circuit but left it on the block, so the
electric isn"t pumping through it but it covers up
the hole in the block. The electric pump made my
truck probably the fastest starting 90 F250 you"ve
seen. It"ll get the fuel primed up and air free
in the time it takes for the glow plugs to fire.
Works well for me.

 

[Feron]

I have a 1995 Ford 7.3 PS I was having the same trouble. Mine ended up being the starter. The 7.3 PS has to crank 600 rpms so the high pressure fuel pump will pop the injectors.
I installed a new starter and solved the problem.

 

[LJD]

7.3 IDI (and 6.9) has two check-valves factory installed in the fuel system to prevent drain-back and hard cold starting.

1. is what you are calling a "check valve" that screws into the top of the injection pump. It prevents fuel drain back and also regulates internal pump housing pressure at 6 PSI. Stanadyne calls the part a "housing regulator valve."

2. the check valves in the mechanical fuel pump that feeds the injection pump.

Besides these two check-valve systems, Ford also use the Schrader-valve that can cause air leaks in the fuel - but as I recall that's only with the older trucks with the pair of round fuel filters (primary and secondary).

 

[LJD]

If you haven't read the article posted at the bottom of this message already, read through it carefully (it's not written by me).
Ford and GM diesels with mechanical fuel pumps were known for fuel drain-back problems and the fixes were pretty much the same for both. They both used the same Stanadyne fuel injection systems. Ford's fuel filter system is a little different because of the many Schrader valves that can get air leaks.

Here's the guy's article covering problems similar to what you've described:

Stall after starting (especially after hot-soak/cool-down) then hard start
Air intrusion into the fuel supply system. Usually, the source of the fuel leak can be determined by the time from when the engine starts to when it stalls. On 6.9 engines with a firewall-mounted water separator, the engine will start and run for upto a couple of minutes before any air which may be in the separator reaches the injection pump. The 6.9 water separator is prone to leaks, both fuel and air. The best cure for this is to replace the OEM seperator with an aftermarket one (much cheaper--$30-$60 vs. $180), or remove it and its hoses and connect the line from the tank to the one running to the lift pump. Since it's not recommended to operate a diesel engine without a water separator, replace the fuel filter with the 7.3 type filter/water separator assembly. You can either purchase the header and sedimate bowl from Ford or a wrecking yard and install a new 7.3 filter. Another option is the Racor fuel filter/water separator kit. This kit contains a filter which fits on the original header and has a water sedimate bowl which screws onto the bottom (@ $35). The filter can also be purchased separately (@ $20), and you would want to keep a spare on hand as the replacement filter would not be available at your local parts store.
The 7.3 filter/water separator can develop fuel/air leaks at the fuel heater and restriced filter sensor or the filter drain (all three are servicable) and water in fuel sensor o-ring. The air bleed Schrader valve can leak on either filter.
The next common area for air leaks on both the 6.9 and 7.3 engines is at the injector return cap o-rings and hoses. This will cause the engine to stall after about 30 seconds of running if the air is able to travel into the fuel filter. On 6.9 engines the return line from the filter should be long enough to loop about four inches above the filter.
The 6.9 can be modified to have a check valve at the fuel filter return to prevent air from entering the filter. A 7.3 Econoline filter outlet fitting (E8TZ-9C402-A) can be installed in place of the original outlet fitting. An early 3/16" 7.3 filter return orifice with a "flapper" valve can be installed into the port ment for the E-van's restricted filter sensor.
On 7.3 engine the filter return orifice contains a check valve. This check valve is usually a rubber flap inside the fitting, and if this fails air is drawn into the filter as the fuel cools and contracts. This can be detected by removing the fitting and trying to blow through it from the hose barb end. If you are able to blow through it from this direction, it needs to be replaced. Seal the threads on the orifice with Loctite 515 Gasket Eliminator or PST. There are two different flapper valve orifices--3/16" and 1/4"--and the correct one needs to be used with the coresponding hose size or leaks may occur. Starting in 92 a 1/4" filter orifice was introduced without a flapper valve using a spring and plastic check ball. The spring-and-ball and flapper orifices are not interchangable; they have different headers. Also, the correct size return lines hose needs to be matched to the injector caps and the proper clamps used--not worm-gear, this will distort the hose; either OEM spring clamps or fuel injection system screw-and-band type. When replacing injector return o-rings on one injector, you should replace all on that cylinder head as they tend to leak after they have been disturbed. Use silicone dielectric grease to aid in reassembly and some times it helps to install a third o-ring between the return cap and injector line nut to keep the cap in place.
On the fuel supply lines at the filter inlet, filter outlet and injection pump inlet, there are seals which can allow air to enter the fuel system if they become deteriorated or dried out, even if there are no visible signs of fuel leakage. If there is a leak on the line between the filter and injection pump, the engine will seem to try to start, then become hard to start. Note that there are seals of the same type on the injection pump return line at the injection pump and at the return line collector fitting on the rear of the engine (some applications).
Less common areas for air leaks are the injection pump outlet check valve and the fuel lift pump, but both have been know to happen. Using clear hose on various sections of the fuel suppy and return systems can usually pinpoint the area of the air leak. Install the clear hose at the suspect areas, start the engine to purge any air, then allow to cool. Watch these hoses for large air bubbles or pockets when starting the engine to determine the origin of the air leak. Also allow the engine to come up to operating temperature to look for air leaks which may occur when the system is hot. These may migrate into the filter and cause a hard start concern.

Engine stalls at stops or when deprsessing clutch
Stalls returning to idle after snapping throttle open. Injection pump problem caused by poor quality or contaminated fuel. Check for presence of water in the fuel--removal of the injection pump governer cover may be necessary to find contamination, but is not advisable unless you have experience. Check idle speed setting and injection pump timing, as well as cold timing advance--timing should advance at least 2 degrees with 12 volts applied to the rear solenoid terminal. Adding Stanadyne's All Season Diesel Fuel Conditioner may cure this problem, but if it persists, or if there is no cold advance, replace the injection pump. Recommend that the Stanadyne All Season Fuel Conditioner be used periodically to prolong injection pump life.

 

[Brad Gyde]

Thanks for that article..

I have already replaced the factory water trap with a spin on filter base and filter.. It's due for it's routine change however..

I have the 7.3 filter and water sep. combo, however, I have done away with the aluminum base that would thread on and went to a NAPA/Wix one piece replacement, seeing as the "water in fuel" light don't work anyhow.

As I had said, I changed the return check valve on the pump Friday.. I blew through the old one as described, and I would get bubbles when submerging the tip into some liquid (I used a soda bottle cap filled with fuel), therfore making it faulty per the article.

I just came in from wrenching.. I pressurized the fuel tank and depressed the schrader valve a few times until I got fuel and not air. Hit the glow plugs.. truck cranked for 15-30 seconds and started as it usually would (just a lot less cranking as opposed to normal)

I paid CLOSE attention to the smoke tonight, since I was in the shop it was easier to see than when out in the open.. The smoke started a dark grey (nearly black) and faded to lighter and then came nearly invisible.. I'm assuming I pushed the fuel from the injector lines into the cylinder (as it likely usually would) then hit a "lean" spot, then things went to "normal operating conditions" as it pushed what air was in the line through..

I believe somewhere I have a leak still.. I noticed I had a "wet spot" on the Y pipe nearer the passenger side, and a spot on the floor the size of say a silver dollar.. It didn't seem to be oil, nor trans fluid, nor did it smell of fuel.. There was a leak in the valley I corrected the other day however. I tried to trace it, but lose it behind the firewall area.. Tomorrow I plan to look into the o-rings and return fittings.. and the o ring under the nut sounds like a good idea.. I'm also going to put a good eye to the mechanical pump area.. would be nice if it was a touch easier to access..

Before I pulled the 6.9 the truck was a good starter, ever since the engine swap it's just got worse.. and most all of the fuel system stuff I'm looking at now was new then..

Brad

 

[LJD]

Many types of leaks can cause the problem.

Last year I pulled the injectors out of a 1985 F250 with a 6.9 that ran and started great. This was routine maintenance. I pulled all eight injectors out and installed brand new nozzles. Only cost $8 each. I then put it back together with a Dipaco return-hose return fuel hose and T-fitting kit. Worked good for a few weeks and then . . . began to start awful if it sat overnight. I saw NO visible leaks at first. Finally after a few more weeks those cheap braided-rubber hoses that came in the Dipaco kit were leaking all over the place and some were falling off. NO tension fit. The hoses were about as bad quality as I've ever seen. I finally ordered 20 feet of much better diesel return hose from McMaster-Carr. Putting on those new hoses fixed my problem on that truck completely. That took me by surprise, but fixed it just the same.