View Full Version : Slow to start after sitting overnight

10-30-2018, 03:02 PM
I have a 2002 T1N. Has always started great, hot or cold.

More recently I'll go to start the van after it sits overnight or longer and it won't start right up. It has to crank an extended time or two before firing and running perfectly.

Throughout the day I can cut the van off for an hour or two and it restarts properly. Just not after sitting a long time.

Aqua Puttana
10-30-2018, 03:25 PM
Off the top of my head, some things to consider.

Check the battery voltage after sitting. Proper cranking speed is necessary for reliable starting.

Air leaks in the low side fuel filter/lines. Check for bubbles in the clear hose.

Bad internal seal on the fuel rail solenoid. Check fuel rail pressure to be 2900+ psi while cranking.

An injector issue. Perform an injector leak off test, but realize that the test is not 100% conclusive as to overall injector health.

:cheers: vic

A sticking EGR can also affect starting.

10-30-2018, 04:08 PM
What Vic said...

What are ambient overnight temps? (how cold is cold??)
Does your exhaust give a puff of white smoke when the engine catches (no combustion/glow plug issue) or black smoke (lack of atomization/air/poor fuel rail pressure)?


10-30-2018, 09:26 PM
Wiring to, or the condition of, the cam shaft position sensor ...

--dick (but i'd suspect a fuel issue first.. )

10-30-2018, 11:00 PM
I had the same problem that got worse over time. It would start ok up to seven hours after running. Left overnight it was a major operation to start it.I was told I had leaky injectors and air getting in the worn pipe at the filter. Had the pipe and filter replaced with no improvement. Two injectors replaced sorted it.

10-30-2018, 11:35 PM
2002? My first inclination is to look at leaks in the fuel lines or the fuel filter.
The camshaft sensor is almost always fails when it's hot but works fine when cold. This sounds like it's the opposite situation.
How old is your battery? Does the van crank over slower in the morning when it has a hard time starting?

11-02-2018, 12:35 AM
Battery is maybe a year old. Crank speed etc. is fine. Sometimes it'll start and cut right off, second or third crank and it'll fire up and idle perfectly. Just takes a bit of cranking to get it going like fuel leaks down after sitting overnight. Temperatures are not cold. It did it in the summer, it's doing it now. Van always started good even in much colder temps before. Wasn't sure about fuel pump, fuel pressure, valves that could allow fuel to leak down etc.
Fuel filter is changed every 10,000 miles and I don't see any air bubbles in clear hoses. Just fuel.

11-03-2018, 05:53 AM
Perhaps your low pressure fuel pump is on its last legs and is losing prime overnight?
I believe your engine has a low pressure sensor above the filter.. may be worth watching the value during a cold vs warm start? You could also see if clamping the fuel line overnight helps.


11-03-2018, 04:22 PM
Hi Dave,

Is #29 the low pressure fuel pump? Bolted up high right on the front of the motor?
In this link: https://ibb.co/ju5PCf

Do you see the low pressure sensor you refer to in the link so I know what it looks like when I look above the fuel filter? You mention watching the filter cold vs. hot start. What do I watch for?

Also where/how would you recommend clamping the fuel line?

Thank you

11-03-2018, 04:43 PM
I’ve got an om649 so am not as familiar with your engine, but yes, #29 is the low pressure pump. I don’t know for certain there is a pressure sensor, but it would be between this lift pump and the HP fuel pump. Look for wiring; Check the ECM pinouts in the service manual for the sensor signal.

Clamping the line between the filter and lift pump would help hold fuel and diagnose leak-back, but the clear lines may not be good candidates as they may be damaged by clamping. The rubber hose from the tank into the filter should tolerate it better?

11-07-2018, 09:12 PM
Today after sitting probably less than an hour after driving to the job the van was difficult to start. I thought I was going to have to get towed. I cranked several times before it fired and ran perfectly.

I have not seen any air bubbles in any of the clear fuel lines.

Cranking speed is nice and fast.

Would a bad injector or two cause this hard of a time starting yet perform flawlessly once started?

11-15-2018, 12:17 AM
Still having trouble:

I replaced the fuel filter.

After bleeding the fuel filter and running the van I noticed continuous air bubbles in the fuel line while running.

So I replaced the clear fuel line to fuel pump line as well as some o-rings and the return valve (plastic T looking thing) on the fuel filter and reprimed.

Now I can't even get the van started.

11-15-2018, 12:36 AM
Did you use an oem FF? After you replaced the lines did you get a good prime on the fuel line circuit? NO bubbles in the line all the way up... if you want to put this issue to bed you may want to consider installing an inline fuel pump down stream from the fuel filter. Something at like 15psi. Nothing extravagant. Just something to push fuel up the line to eliminate vacuum leaks (of course if you have a vacuum leak at the tank this will not help).

Ps - I have an om647 motor with the in-tank lift pump but did encounter this once on someone else’s van and had to work through this issue. I learned my lesson on a Napa FF. They stated it was oem, but when I finally got my hands on a mbz ff the difference was obvious at the water in fuel sensor mounting point which is the typical spot where vacuum leaks occur.

11-15-2018, 01:51 PM
I have not been using an OEM fuel filter. Never had an issue before and this didn't occur right at a fuel filter change. I did replace the fuel filter anyway just to try to eliminate that as an issue. Issue was still there and old filter was clean so I also replaced the clear fuel line as well as the O-ring that goes on the water sensor etc.

I've also never had any trouble with it not having an electirc pump before except for fuel filter changes are a pain to reprime. This is worse than that, though, so I wasn't sure if there was a good way to test the lift pump or another area to look for the issue?

11-15-2018, 10:33 PM
...sure if there was a good way to test the lift pump...

You donít have a lift pump thus your vacuum leak issues (most likely VL issues)..

11-16-2018, 01:21 AM
Can you use your old clear line to rig up an attempt to push fuel into the LP pump *outlet* ??
That would put the pump’s valves to the test as it shouldn’t pass any fuel backwards.


11-16-2018, 05:27 PM
I fuel filter changes are a pain to reprime.

If you have access to a MityVac, priming is not that difficult. See https://sprinter-source.com/forum/showthread.php?t=57440

Also, if you have been cranking for a while, if your battery's voltage drops below 11.5 volts the engine may not start.

11-17-2018, 12:21 AM
I used the mightvac on the output of the lift pump and primed. I knew I had good clear fuel to this point so I then connected output line and it still took SEVERAL attempts but once it started it ran 100%.

Yesterday I ran about 5 minutes and didn't see air bubbles in the clear line from the fuel filter to the lift pump.

Today I attempted to restart and could tell it was taking more cranking than it should so I assume it has gotten air into the system somehow?

I replaced the "valve" on top of the filter that connects to the return line but not the rubber line itself. I can replace the section that goes from the filter to the tank. What about the other end? Maybe the system is just still getting air in it and leaking down from one of these lines?

Voltage is good. If I crank more than a couple of times I put it on the charger to keep battery up while cranking.

11-17-2018, 12:23 AM
Also, the clear line on the output side of the lift pump. It appears to go to a "TEE". One side goes to the high pressure pump.

Where does the other side go?

I'm not sure if I need to replace it or not as it's on the output side of the lift pump, it seems if this was where the leak was it would show a fuel leak since it's the pressure side.

11-17-2018, 12:47 AM
Something that has worked for me on other air leak prone systems is to use loctite 518 on any fittings with a metal surface. It plays well with O-rings, and won't cure if it breaks off into the rest of the fuel system.

The output side of the LP pump is up to 50 PSI during operation. However if there is an air leak, it can allow the pump to loose its prime when sitting. Look for any minor fuel seepage on this side of the LP pump fittings, as a small fuel seep is a moderate air leak.

11-17-2018, 02:04 PM
Will do, thank you.

11-17-2018, 06:53 PM
I have never gotten the lines to seal the first time when replacing fuel filter. I've always had to re-seat or tighten things at least once to get bubbles or slow air infiltration to stop.

I have also had problems with some brands of filters, they are not quite right and the connections don't fit well. Get German brands.

11-19-2018, 02:09 AM
Thanks for the tips.

I tried blowing back in the output of the lift pump and air blows through the lift pump right down the clear line to the filter. I'm guessing that means the check valve in the lift pump is bad?

The lift pump does have good pressure and fuel output but maybe bad check valve?

11-20-2018, 05:06 AM
Have you read this thread?


bill in tomahawk

james h
11-25-2018, 12:33 AM
Perfect timing on this thread. I have the same issues on a 2002 3500. Hard starting after sitting and bubbles in the fuel line. Kept getting worse until it wouldn't start. The sprinty has been down for 6 months and I've just got around to digging into it. It's good to see the T1N's still get excellent attention from the forum. I will be working through the possibles for the next week including the filter sans water drain/sensor swap. Thanks all!

12-30-2018, 02:49 PM
Thank you for the fuel filter link.

I still have an issue.

I have replaced all 3 clear fuel lines as well as the lift pump. I think the new lift pump helped but the van still takes several attempts to start.

Once it starts it runs 100%.

There are no longer any air bubbles coming up from the fuel filter.

The "Y" or 3 way shaped clear line coming out of the lift pump goes to the high pressure pump as well as around the side of the motor to what I assume is a fuel pressure sensor.

This line has an air bubble in it.

I tried loosening the 24mm brass screw to bleed the air out of the line with the van running but that line still has an air bubble in it.

Aqua Puttana
12-30-2018, 03:27 PM
Have you checked the fuel rail pressure while cranking?


Off the top of my head, some things to consider.

Check the battery voltage after sitting. Proper cranking speed is necessary for reliable starting.

Air leaks in the low side fuel filter/lines. Check for bubbles in the clear hose.

Bad internal seal on the fuel rail solenoid. Check fuel rail pressure to be 2900+ psi while cranking.

An injector issue. Perform an injector leak off test, but realize that the test is not 100% conclusive as to overall injector health.

:cheers: vic

A sticking EGR can also affect starting.

12-30-2018, 04:10 PM
The Sprinter I just purchased had similar issues. The previous owner replaced almost everything in the fuel delivery system, then gave up on the van. I performed the injector leak-down test, and 3 injectors failed badly. Replaced them (the other two showed no signs), and she now starts like a charm.

12-30-2018, 06:36 PM

Thank you for this info.

I replaced all 3 of my clear lines but am having trouble getting the air out of the one you call the "black" line, the 3 way shaped "T" or "Y" line.
An air bubble remains just before it gets to the fuel pressure sensor.
I tried cracking the 24mm nut on the fuel pressure sensor until fuel comes through with the van running but once I tighten it back an air bubble seems to remain in the clear line.

There doesn't seem to be anywhere for the air to work out since it just goes to a pressure sensor. Can you advise me?

12-30-2018, 09:53 PM
If you are referring to the connection low and behind the manifold - with the van not running the bubble should flow up to the low pressure pump as diesel has low surface tension.

If it is staying down while the van is running, that to me implies that the bubble is originating from down there and the flow is keeping the bubble down. After a prime, try having a helper look at the lines while starting up the van. Either the connector is not set properly or the O-ring has become damaged or deformed would be my guess. A little silicone is Dr. A's advice on preventing damage and/or deformation of the O-ring on these lines.

These lines are sooooo frustrating....

01-02-2019, 12:33 AM
That's a good point.
It seems to stay at the high spot right where the clear line goes behind the intake manifold. It would have to go down and then back up to the lift pump or "T" junction area. Do you think it will do that with time or somehow I can bleed around the low pressure pump and get it out?

01-15-2019, 10:25 PM
I think all the air is bled out now. Van has been run a fair amount and runs 100%.

The problem is when I go to start it, sometimes it will fire for a second then nothing.

Longer cranking seems to be less effective than multiple short bursts. If it doesn't fire right up after a second of cranking, or if it fires once but doesn't start. I cycle the key and try again.

It has been starting after about 3 short cranks.

Does this sound familiar or indicative to anyone?