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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 23821
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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My 4.0 1996 ford exp. has a rough first start up in the day,

Customer Question

my 4.0 1996 ford exp. has a rough first start up in the day , then smooths out. this problem occurs only once in the morning. hope to talk with a tech. who had the same problem in the past. Xxxxx Xxxxxx
Submitted: 1 year ago.
Category: Ford
Expert:  Tim Mohr replied 1 year ago.

Hi, my name is ***** ***** is caused by either a leaking injector, that leaks down into the cylinder as it sits, and then it has to burn off the extra fuel in the cylinder, then runs smooth the rest of the day, or it is loosing it fuel prime overnight, and then once it fills the lines with fuel, it runs smooth, when its running rough is there any grey smoke coming out the tail pipe?

Customer: replied 1 year ago.
no gray smoke coming from the tail pipe. the computer had triggered a p0402 code last month. thats why I checked out the ERG system. also, in the past , the car did not want to start when pointing forward on a down hill grade.
Expert:  Tim Mohr replied 1 year ago.

ok, if there is no smoke, then its most likely a bad check valve in the fuel pump, causing it bled back as it sitd overnight, hpw long does it run rough on first start up?

Customer: replied 1 year ago.
it runs rough from 30 to 45 sec. then smooths out with no start up problems for the rest of the day. how much vacuum should come through the EGR solinoid 5 in Hg ? the fuel pump had been replaced. the fuel pressure was checked at the same time.
Expert:  Tim Mohr replied 1 year ago.

The egr valve does not open when its idling, so I dont think the egr is the problem, if the pump is new, then this rules out thecheck valve, when was the pump replaced?

Customer: replied 1 year ago.
the fuel pump was replaced in June of this year. I can have them re-check the fuel pressure to see if their is any fluctuation in pressure.
Expert:  Tim Mohr replied 1 year ago.

we need to see what it is on the first start of th morning, to see if its losing the prime overnight,Tim

Customer: replied 1 year ago.
first start-up still the same results. I can wait until the afternoon to test the first start-up to see if the air temp sensor is ok. the multimeter readings to the sensor are good. should I disconnect the battery to reset the computer. maybe try some fuel injector cleaner ? any ideas?
Expert:  Tim Mohr replied 1 year ago.

Did you check the fuel pressure on first start up?

Customer: replied 1 year ago.
no ! I have to have to get a gauge and have my son help during start up. what residual fuel pressure should I expect and what pressure should I expect at idle ?
Expert:  Tim Mohr replied 1 year ago.

it shou;d come up to at least 35 psi, as soon as you start it,Tim

Customer: replied 1 year ago.
found the problem ! malfunctioning EGR solinoid . I found out that the solinoid was open during initial start up and lasted for a short period of time, allowing the EGR valve to open and close during initial start-up. I hope this information can be of value. respond if you will.