Starting problem in cold weather

SHAUGE

MEMBER
1994 JEEP GRAND CHEROKEE
4.0L
6 CYL
AWD
AUTOMATIC
200,000 MILES

Okay, here is a tough one for you. The last two winters (2014/2015) my vehicle was getting gradually harder and harder to start in the Minnesota winters. As the season got colder it took more and more cranks to get it to turn over. It did not seem to be an electrical problem because the battery was not that old and I had it tested, and connections were good. Starter had been replaced three years prior, and ignition coil replaced about two years prior.

So I figured it was fuel line related so over the summer I replaced the fuel pump and connectors, and put in a new fuel filter. As the 2016 winter came upon us the same old thing started happening: when the temp dropped below forty degrees it took two or three cranks to start. Below thirty degrees it took five or six cranks. And below twenty degrees up to eleven cranks!

Then I was looking around online for a forum where others talked about a similar problem and one guy described the same problem, but then suggested this: turn the ignition to clicks to the on position, but did not crank it. Wait to hear the fuel pump kick in, then crank. I tried this and low and behold, it started on the first crank! This was good news, but still begs the question: what is it not working right that I have to do this? Today in Minneapolis it is minus five degrees, and it took over two minutes for my fuel pump to even engage. Now I am really stumped. That sounds like an electrical problem. Can you give me some ideas?

3 Replies

HMAC300

MECHANIC
48,601 POSTS

Take the ASD relay and fuel pump relays out and check for corrosion on relay prongs and where it plugs in and try to clean as much as possible off then use dielectric compound on prongs prior to plugging back in. The fuel pump relay also supplies power to the O2 sensor which is heated which may be the problem because in cold weather may be requiring more power to heat or O2 sensor is going bad it is the one below exhaust manifold. Also, because this is a 4.0L check at rear stud on head and see if harness has worn through there as it hits against head stud and wears through the harness. Which may giving a partial ground on a circuit.