Hello- I'm searching all over the forums and internet for a clue why my 7.3L IDI turbo (early '94) all of a sudden is hard to start. It doesn't matter if it is hot or cold or if I shut off the engine 5 minutes ago. I might have to engage the starter 3 or 4 times for 15 seconds each before it starts. (Of course this is wearing down the batteries and heating the starter a lot, I'm sure). Once started, it runs just fine. Fuel tank selector position doesn't matter. I think it is probably a fuel delivery problem (and not a glow plug issue), in that once it starts it does NOT blow a pile of smoke. (Earlier in the year my glow plug relay was flaky and when it finally worked, a lot of smoke came out, telling me the cylinders were full of unburned fuel. This is different, hence my thoughts on no fuel getting into the cylinders.) I don't see any obvious fuel leakage around the injectors. I suspect that if there was air leaking in somewhere it might be rough running when it did start, which it is not. I read in some forum that there was some kind of fuel drainback valve that could cause this, but I can't seem to locate any such valve in my Ford Engine manual. Some helpful pointers would be appreciated. Thanks.

 

Um... How quickly is your starter turning over? Can you post a video?

A worn IP can cause this, but I've found that even with a new IP, you can have a starter which cranks, but doesn't do it fast enough to fire it right off.
What tends to happen is that there are 4 brushes in the starter. One of two things can happen:
1. One brush(or pair of brushes) wears more than the other. You get a case where the starter is running on one of two sets. When this happens, the speed is lower and it sounds like a low battery(but cranks at that speed for 60 seconds or more).
2. Corrosion/buildup layer on the contacts inside the starter. From use(or leaks), you get some sort of crud between the brushes and the contact area. This slows down the starter as it's not getting full power.

I've run into this problem several times as old(er) starters wear out. New ones aren't immune, either... there are plenty of crappy rebuilds about, either because they didn't replace the brushes or the rotor is so poorly made that the brushes wear out really quickly.

On my truck, with a /good/ starter, it'll fire off within 2 revolutions of the engine. No cranking to speak of, hot or cold. When my last starter went, it took 15 seconds or so before it would catch. Just before I replaced it, I tried to start it after it sat for half an hour... cranked it for almost 30 seconds and nothing. Pulled it up a hill, bump started it and it fired right off. Replaced the starter the next day and it fired right off and hasn't had that problem ever since.

Do you have a stick? If so, try bump-starting it with a bit of a hill. If it fires right off(especially warm), I'd suspect a starter.

 

Thanks for the reply, but the engine is turning over just as fast as it always did. In the past, like your engine, it always started within a couple of seconds on the first try. It just stopped doing that recently. Also, I am charging the batteries with a charger yesterday since I know that short trips will not recharge the batteries. Yesterday, after 3 stops on a short trip, the truck almost didn't start. After trying to start it by engaging the starter 4 times and on the 4th time, I was expecting the starter to either burn up or the battery to quit, it suddenly fired up while cranking at relatively low speed. I had read that if the engine is not turning over fast enough, the injectors won't disperse fuel, but I don't think that is the case here. Is there a way for the fuel to drain back somehow only with the engine off for 5-10 minutes and still run OK when I get it started? I would think if there would be an air leak, then I might have rough running, which I don't.

 

A bad fuel pump, bad housing-pressure-reg-valve on top of the pump, etc. can cause fuel drain-back. But when that happens the engine would skip and miss a little at first start. If you engine runs fine once it DOES start - you've got injector pump issues. That assuming at least 9 volts of DC power is always getting to it. If the main part of the pump - the distributor section i.e. "head & rotor" is worn - the engine can run fine but be very hard to start since 300 RPM cranking speed is not enough to overcome internal leakage. Once running there is more then enough fuel to overcome the leakage. But that sort of thing is usually much worse when hot then cold. You also may have a simple linkage hang-up problem with the fuel solenoid. Inside the pump - the fuel shut-off solenoid has NO direct connection to the valve that turns your truck "off" or "on." So even if you hear it "click" it does not mean it is working. The solenoid is bolted to the top cover of the pump and is easy to get too. When it gets 9 volts or more of power - the magnet pulls a metal arm out of the way so the fuel-valve can be pulled open by a spring. It may just be getting stuck. That fuel shut-off or on valve is easy to see once that top cover is off (called a metering valve).

 

Thanks, I was just about ready to ask if it could be a Fuel Shutoff Solenoid issue, when I noticed your above feedback. I was looking over the truck this morning and wondered about that. So you are saying to remove the top cover of the FSS and look inside to see the metering valve? Any way to visually see if anything is wrong, or do I just need to just replace the metering valve? This is, of course, assuming I have at least 9 VDC on the solenoid. Knowing about solenoids (in non vehicle related stuff), I also know that solenoids can be flaky or partially internally shorted or have mechanical problems. I see in the Electrical Manual that the FSS, when energized (in Start or Run key positions) allows the fuel to flow. Will check on voltage and get back to you.

 

The fuel metering valve is just a solid chunk of steel. It is round and fits in a bored hole with very close tolerances. It rotates back and forth with "no fuel" at one end and "full fuel" on the other. It's not something you'd want to replace. I'd check it for sticking and make sure it moves freely. I'd be more suspect of the linkage or the fuel-shut-off solenoid. I have never seen a fuel-solenoid actually go bad either and I watched them evolve three times since the early 60s. But the newer ones like used in our trucks can suffer from a metal plunger that sticks. It is just a metal rod that rides up and down inside a round plastic-lined bore and I've seen a few get sticky and catch at times . I have also seen solenoids short out but that is because of the rubber isolators where the electric studs protrude through the top-cover. Not the windings themselves.

If it was mine - I'd pull the top cover off and check the solenoid plunger, shut-off linkage and the fuel metering-valve for free movement.

 

Holy cow! I'm totally blown away by the completeness of your answer along with pictures no less!! Thank you! I'm wondering if I should spray some lubricant inside to help the linkages, etc..., like WD-40 or a silicone spray, etc?? Also, upon replacing the cover, I assume reusing the old gasket should be OK as long as the screws are tight enough?

 

Everything in there is already lubricated by diesel fuel. The cover does not use a gasket. It uses a rubber ring so re-using is usually no issue.

 

Hello folks - There is a possibility that either Macrobb hit the nail on the head, or that I have an intermittent problem possibly along the other lines that Jdemaris suggested. After almost getting stranded the other day with multiple short drives and about 2-3 stops, I decided to put a trickle charger on the batteries all night long. The next day I disconnected the charger, but didn't use the truck. About a day or 2 later, I decided to use the truck and it started right up (within a second or two upon cranking (pleasant surprise!!)). I have now started it up 3 more times, driving it about 20-25 minutes each and one time for just 1 minute. No problemo! I really didn't notice a big change in cranking RPM between when it started working again and when it initially started giving me problems. Of course, when I had problems starting it after the initial instance, it was obvious that the drive times did not have enough time for the alternator to fully charge the batteries. I'm in the process of moving over the next month to another state and will not have time to tear into the truck. If, for example, it gives me a starting problem again after driving for at least 20-30 minutes, then I know I have another problem other than a lower battery charge. (PS- the voltmeter tells all when trying to start and when charging after starting. Too bad there isn't an ammeter in the charging circuit, but higher than middle voltage when driving tells me it is charging the batteries.) I'll report back in later. Thanks for now.

 

One thing-- the stock volt meter isn't the best. Granted I've done the 3g alternator mod but my volt meter reads only 11v when driving, but a real meter on the terminals is over 13.5v.
I remember stock that it was closer, but still read about 1v off or more, which is a world of difference in electrical systems.

That said, the other posters have great info.
The easiest way for me to notice my starter slowing down is this:
It SHOULD spin faster than you can count in your head. Can you mentally count the revolutions? Too slow. Mine is currently in that state, I'll need to pull it soon and get after the brushes/contacts.

On the other point, I've also had worn internal tolerances and they are certainly more noticeable on hot/warm fuel than cold, since the viscosity goes down a lot with a 200 degree engine under the IP.

Could be both, could be starter. Could be voltage regulator-- what's the voltage from a real meter say when it's running at around 1000rpm?

 

Thanks for that tip. As I recall, it does turn faster than I can count in my head. Also, I just use my voltmeter as a relative indicator of charge. It tends to sit dead center when the batteries are in top charge condition. During the starting episodes I had recently, after I FINALLY got the engine to start, the voltmeter was reading higher than dead center obviously indicating heavy charging (higher voltage on the battery terminals).

 

Well... the verdict is finally in. MacRobb nailed the solution. As you can see from my earlier posts, I thought it was the battery, since I had taken some short trips and when I topped the battery off with an overnight charge, I had no problem starting. I then just moved from FL to NC and within 2 weeks the engine got a LOT worse to turn over. It wasn't the batteries, but turned out to be a bad starter. I replaced the starter and the engine turned over SIGNIFICANTLY faster. Thanks all.

 

alt went out on my van 138000 looks to be original, its 25 years old so new one 100 amp good to go found it cuzz she turn slow one morning, almost didn't get her started to get home from work lites were kinda dim checked voltage 11 so fixed it next day..

 

Only read first post, on lunch. My humble internet opinion is lift pump and/or air intrusion. The only thing i can think of that fits both hot and cold hard starts. Albeit, after sitting for only 5 min and not starting.... doesnt really fit air intrusion usually it takes a little bit longer, but if a return cap or something broke leaving a big hole in the return... could happen.