2000 ford 7.3 won't starts cold new glowplugs still starts hard cold?

There may be more than 1 problem. The Timer for the Glowplugs adjusts itself for the temperature of the engine and surrounding air temperature. It is suppose to keep the timer going longer for a cold engine than a warm one. But it does need to heat the Glowplugs to atomize the fuel, then compression takes over.

If the Glowplugs have not been inspected lately, it would be a good time to do it. To test, use a jumper cable with care not to damage the threads of the Glowplug. Usually clamp one end of the jumper on the base of the Glowplug and briefly touch the top where the wiring plugs in.

The Glowplug can melt, but you want to see it glow in a short period of time and uniformily with all 8. Any that stay dark are bad, subpar will take longer than you have and will not fully atomize the fuel before they lose power from the timer.

Another problem can be the gating in the Turbo. There should be clean passages for the valving to seal when the Turbo closes. If the Turbo does not close, the exhaust compression may leak into the cylinder too early before a fuel charge is atomized. Since the Glowplugs are barely on for a hot engine, it will complicate starting.

Since your engine starts great when cold, fuel line integrity and the fuel system should not be a problem. Surging at 55mph is probably due to the Turbo.

Check your Vacuum levels at a convenient tap and see if the Vacuum bleeds off quickly or holds pressure for awhile.

Please rate my info and I hope I have been helpful.

This is not to hard to solve. The outside airtemp determines how long the Glowplug timer works for absolute cold starts. Starting a warm engine is affected by underhood temps.

The Timer Relay will pulse power to the glowplugs. If the glowplugs are good, it is enough to preheat the cylinder for firing.

To tell if a glowplug is good is a matter of comparision between a new glowplug and a worn glowplug. YOU CAN MELT A GLOWPLUG WITH THIS TEST, but you remove the glowplugs, get a set of battery jumper cables and place one jumper to the base of the glowplug USING CARE not to ruin the threads on the glowplug.

You do not want to arc the spark on the glowplug threads. You want your fixed jumper connector locked on the base of the glowplug. The other battery cable jumper is touched to the top of the glowplug where the arcing occurs. This will not hurt the contact point if done properly.

You compare the "glow" of the old glowplug to the "glow" of the new glowplug. Bad glowplugs stay dark or operate at a darker color.

The Timer Relay gives you pulses and that is all the glowplugs get to heat up. This is what you simulate in your test. If a glowplug operates in a dull or dark condition, it is bad and throw it away. You want all glowplugs to readily light up when power is applied.

The other 2 parts to the system are the Timer Relay and the Power Relay. The timer gets its power from the Power Relay and the Power Relay is like a starter solenoid. The Power relay gets a tickler charge when the keyswitch is held to Start.

There are sometimes extreme cold Timers that hold the power longer tothe glowplugs. I do not have the Specs to tell you if your Timer is kicking out to soon.

I hope my solution helps. I have told you how to test your glowplugs. The timers are affected by air temperature and that makes it difficult to say if it is working long enough. If you know the glowplugs are good, and the timer shuts off before the glowplugs heat up, then you need a new or different type of timer.

Hello, The diesel engine relies on Glowplugs for the first start in the Morning or a cold start at anytime.

The Glowplugs themselves can be bad, but there is a Timer which determines how long the Glowplugs will stay on. Before the Timer is a Glowplug Relay which gives the Timer its power to operate. The Ignition switch provides power to the Glowplug Relay.

You disconnect a Glowplug wire, put on a test instrument (either a testlight or Voltmeter) and look to see what happens when you initiate a start. If the testlight lights and cycles a few times like a pulse, then the power supply is good. If not inspect the Timer and Glowplug Relay for continuity

If all the pulses seem to reach the Glowplugs, then most likely the Glowplugs are worn out. Test by removing then and connecting battery jumpers. Briefly touch the top terminal of the Glowplug with the Hot cable after grounding the negative cable on the base of the Glowplug, avoiding the threads.

You can melt a Glowplug. But if you find the Glowplug staying dark, then it is bad. Do this for all the Glowplugs and replace the bad ones. Remember the Glowplug only has the amount of time the Timer gives it to work. So if a few pulses do not make it Glow, then replace it. This should fix you up.

Hello, Most likely your Glowplug Relay is bad, and it supplies power to the Glowplug Timer which also may be bad.

Just follow the wires that are on the Glowplugs up to the Glowplug timer. Use a Voltmeter and check if the power wire that goes into this Timer has fire when the Ignition is turned to the RUN position. If there is fire going into the Timer from the power Relay, pull off one of the Glowplug wires and ground 1 end of a testlight and put the other end on the Glowplug wire.

The Timer itself will kill the power after a predetermined time based on Temperature. The colder the engine, the longer the Glowplugs stay lit. If you have power reaching the Glowplug, your power Relay is fine. You just have to observe how quick the Timer stays on.

The Glowplugs only have 1 or 2 chances to do their job at the Start-up. They are needed to make a Diesel start cold. Cold meaning at outside AIR temperature, and engine block temperature. There should be clicks under the hood and the lights should flicker in rhythm to the clicks if the Timer is working.

If you find that both the Timer and Power Relay are working, the Glowplugs need to be tested. They come out like sparkplugs. But you test them either on a special machine or use battery jumper cables. To test, hook one battery cable to the Glowplug base, avoiding the thread. Then take the other cable and arc it on the top of the Glowplug.

Caution, you can melt the Glowplug. If you get a bright glow, the Glowplug is good. If the Glowplug is dark or very slow to glow, it is bad. This should be all you need. Would appreciate a note after you fix it.

Have you checked the glowplug relay.

Sometimes there is a Solenoid inside the Injector pump which responds well to a hammer handle tap. You can also connect a test light to a glowplug wire and see if the Timer is cycling. You need to have the glowplugs working for your cold starts.

If you have fire at the glowplug wire and are convinced you have fuel, you may need to check each glowplug. Remove at least 1 bank at a time. Hook up jumper cables to each glowplug and being careful with the threads clamp the Neg cable to the base and just touch the Pos to the top.

A good glowplug will get with it instantly. A bad glowplug will stay dark or never get up to the best operating heat. Be careful not to melt the glowplugs, but once you find your best glowplug you will see what I mean. Or you can buy 1 new, and compare all of yours to the new one.

Fuel, there are winter and summer blends. You may have gone to a station with Summer fuel.You need to add fuel thinners and water removers to the fuel in your tanks. Check your fuel separator and perhaps slip in a new fuel filter.

I hope this helps get you going.

Hello, there are several things as likely to cause this problem, either spark or fuel.

The glowplugs are needed to make a Cold engine start. You can take a testlight to the glowplug wire of several cylinders and it should light when the engine is put to the Run position. The glowplugs get their power from a Coldstart Timer and it may have an additional relay.

The Coldstart Timer is the part which clicks and makes the lights dim when it is cycling. It also controls the dash indicator and makes the dash light work when the glowplugs are ready. The timer changes the amount of time it cycles according to outside and engine temperature. If you have noticed the "Ready" light vary its timing, the timer is working.

Say you have no spark at the glowplug wire, work backwards to the Coldstart timer and see if it is getting power. Power in, none out, bad timer. No power in, work backwards for a Relay or fuse.

Now if you have power at the glowplug, remove several and test them with Battery jumper cables. Put the NEG on the base and touch the POS to the stem. You can melt them if you overdo it. The longer it takes for the glowplug to glow, the worse it is. Once you find a good glower all tests are relative to the good one.

Fuel problem. If the glowplugs test out, check the fuel. Long start times can mean the fuel drained back to the tank and has to be pulled all the way up front. You can unscrew your fuel filter and see if it is topped off or empty. Then you need to test the lines from the fuel filter back.

It is also possible an internal Solenoid in the Injector pump is sticking. A light tap before starting can indicate this problem if it starts better after tapping the pump.

Thats about it. I hope you find my Solution useful.

Check glowplugs, if they aren't staying on long enough it will have extended crank. Might try cycling ingnition a couiple of times. May aeve some bad glowplugs, relay or possible glowplug wiring harness issue.

check the thermic switch wich turn on or turn off the start cold injector. and the same time the cold start injector. the relay only give courrent tot this ones.

Do mean you have hard time communicating with a scanner at the OBDII connector, if so make sure you power at pin16 at diagnostic connector, also we have seen issue with glowplugs not working properly causing hard start when cold and starts fine after warm-up
You can check for glowplugs operation at initial key-of before cranking by checking for voltage at each glowplug connector with a multimeter.